RISAT-1: Configuration and performance evaluation

Radar Imaging Satellite (RISAT-1) was launched on 26^th April, 2012 and is available to international SAR community and researchers as a source of multi resolution/multi-swath/multi-polarisation SAR data. The first satellite, RISAT-1, carries a multi-mode Synthetic Aperture Radar (SAR) in C-band as the sole payload. RISAT-SAR payload supports variety of imaging modes e.g., stripmap, scanSAR and spotlight. All these imaging modes can be operated in Hybrid polarimetry mode also, making it the first of its kind. The payload is based on active antenna array technology. The active antenna has nominal aperture of 6 m×2m, consisting of 12 tiles which are grouped into 3 panels. The RISAT-1 spacecraft has been built around the SAR payload in order to optimise the spacecraft weight and structure. The satellite is placed in a sun-synchronous orbit with 6 am-6 pm equatorial crossing, to maximize solar power availability. Initial performance assessment indicates very satisfactory performance of the SAR system of RISAT-1 in terms of image quality, calibration, geometric fidelity and consistent product performance and active antenna pattern synthesis. Already from September 2012, data products are available operationally from National Remote Sensing Centre, Hyderabad.