Shuttle Imaging Radar-A information and data availability

The performance characteristics of the Shuttle Imaging Radar (SIR-A), carried aloft on the STS-2 flight, are described and the results of its initial use are evaluated. The SIR-A is an SAR system operated at 1278 MHz (L-band), i.e., a wavelength of 23 cm. A seven panel antenna 9.4 m long was used, and scans were performed at a 50 deg angle of incidence to the center of a 50 km swath. Resolution is 40 m, and imagery is generated on a scale of 1:500,000. Sample images of a Brasilian island and the California coast are provided. Comparisons of the SIR-A imagery with Seasat SAR composite imagery demonstrate that the SIR-A is more sensitive to local roughness and only slightly dependent on terrain slope.