India has launched several satellites with the optical sensors. These optical sensors, have provided data which were extensively used in natural resource mapping and management. However, these sensors do not support allweather imaging. Microwave remote sensing satellites fill this gap. As a prelude to the RISAT-1 mission, ISRO has successfully launched the RISAT-2 satellite. RISAT-2, or Radar Imaging Satellite 2 is an Indian radar reconnaissance satellite that is part of India's RISAT programme. It was successfully launched aboard PSLV-CA at 01:15 GMT on April 20, 2009 from the Second Launch Pad at the Satish Dhawan Space Centre. The ANUSAT student micro-satellite was flown aboard the same rocket as a secondary payload. First day imaging by RISAT-2 was done on 29-04-2009.
The Mini class, low earth orbit RISAT-2, was offered as an off-the-shelf product by Israeli Aerospace Industries (IAI) and ranks among the world's most advanced space systems. Its Synthetic Aperture Radar (SAR) uses a large dish-like antenna to transmit and receive radar signals that can penetrate darkness and thick clouds providing images with 1m resolution. The orbit parameters are given in the following table.
|Frequency||X band 9.59 Ghz|
|Data link rate||620 Mbps|
|Revisit||3 or 4 days|
|Repeat Cycle||14 days|