The last two decades has seen the development from initial concept to commercial systems of a mapping technology based on interferometric synthetic aperture radar (IFSAR). JPL has been actively involved from the initial development and testing of such systems with the NASA/JPL TOPSAR system flown on the NASA DC-8 from the early nineties, to the the most recent dual frequency GeoSAR system system designed to map both the top and bottom of the vegetation canopy and recently delivered to Earthdata International to operate commercially. Each generation of instrument through improvements in hardware and software has steadily improved the accuracy, resolution, coverage and phenomenological understanding. TOPSAR started the radar interferometric mapping revolution with a single frequency C-band system capable of making digital elevation models (DEMs) with a height accuracy of around 3 m and a spatial resolution of 10 m. TOPSAR's area coverage rate is 150 km^2/min which was a major increase compared with then available airborne photogrammetric mapping technology. Based on the success of the TOPSAR system DARPA initiated the development of the the IFSARE system, the interferometric mapping radar designed to a specific set of mapping requirements. ERIM built the radar and JPL provided system engineering expertise and the processor for the system. IFSARE height accuracy improved to the meter level with resolution around 7.5 meters. GeoSAR the latest generation airborne interferometric mapping radar uses a combination of X-band (3 cm wavelength) and P-band (85 cm wavelength) to map the top and bottom of the canopy. The X-band system has height accuracy of less than a meter for much of the swath with resolution around 5 m. By mapping on both the left and right side simultaneously the system's area coverage exceeds 300 km^2/min.
Paul Rosen and Scott Hensley