SIR-C flight hardware: design objectives, actual performance, and suggestions for future applications

The extremely successful flight of the Spaceborne Imaging Radar-C (SIR-C) on STS-59 and STS-68 missions in 1994 has provided a wealth of multiparameter data for evaluating the use of spaceborne imaging radars in Earth science and applications. At conception, in 1985, SIR-C was designed as the evolutionary step between the previous single parameter imaging radars and a multiparameter imaging radar to be flown in permanent Earth orbit. Within this scenario, SIR-C included multifrequency and full polarimetry with a system architecture amenable to graceful degradation over long time periods in space. Included in the design was electronic beam steering to provide not only diversity in viewing geometry but also to investigate beam scanning for wide area coverage at reduced resolution. This paper focuses on the flight hardware with emphasis on the driving design parameters, the system architecture, inflight performance, and some experiences relative to future applications.