Spaceborne Synthetic Aperture Radar: Future Technologies and Mission Concepts

Abstract

This paper provides an overview of the state of the art and future developments in spaceborne synthetic aperture radar (SAR). Today, we are experiencing a golden age of spaceborne SAR, with the number of satellites in orbit increasing rapidly. This paper presents novel technologies and mission concepts associated with innovative imaging modes, which are required to meet the stringent user requirements for improved performance, global coverage, faster revisit times, enhanced spatial resolution and increased information content in SAR imagery. It is shown that key technologies and mission concepts, based on digital beamforming, bistatic and multistatic SAR, distributed SAR and multiple-in multiple-out SAR (MIMO-SAR), will boost the performance and capabilities of the future generation of spaceborne SAR systems. In addition, the paper addresses dedicated mission designs, technologies and orbit concepts that are required to fulfill the specific user requirements. Two main streams in the spaceborne SAR development are presented alongside a trade-off analysis: 1) NewSpace SAR, consisting of small satellites in the 85 to 250 kg weight class with highest-resolution imagery and very short revisit times, and 2) fullfledged SAR satellites with global coverage, high performance and enhanced capabilities. It is shown that NewSpace and full-fledged SAR satellites are complementary in terms of user requirements, and that combining both mission concepts enables novel mission concepts, such as multistatic SAR, opening the door to a wealth of new applications. The paper concludes with an outlook on the future of spaceborne SAR.