Spaceborne GNSS-R Bistatic Radar Remote Sensing, CYGNSS, and Future Missions

Global Navigation Satellite System Reflectometry (GNSS-R) is a relatively new type of radar developed for remote sensing of the Earth surface. It uses GNSS navigation signals such as those transmitted by the Global Positioning System (GPS) constellation of satellites as the radar transmitter. The radar receiver measures alterations in the navigation signal caused by scattering from the Earth surface. The nature of those alterations contains information about the surface, which can be retrieved. The general theory of GNSS-R remote sensing and its historical development is presented, followed by a detailed assessment of the performance and capabilities of the first dedicated spaceborne GNSS-R science mission, NASA’s Cyclone Global Navigation Satellite System (CYGNSS). Numerous follow-on GNSS-R missions are also noted that have either already been launched or are scheduled to be soon. A wide range of science data products and scientific applications of the CYGNSS data are examined. Developments that are currently underway in GNSS-R technology are summarized, and their potential impact on the capabilities of future GNSS-R missions is discussed.