RISAT-1 (short for Radar Imaging Satellite
- 1) is the first of the RISAT series of Indian remote sensing
satellites built by the Indian Space Research Organisation (ISRO). It
uses a C-bandSynthetic Aperture Radar (SAR) for all-weather earth
observation. The previous Indian remote sensing satellites relied mainly
on optical and infrared sensors.
The RISAT-1's SAR radar will be able to see through clouds and work in
darkness, conditions that hamper optical satellites. Its images will be
useful for a variety of applications, from crop forecasting and disaster
management to addressing the country's strategic needs.
The features of RISAT include:
160 x 4 Mbps data handling system
50 Newton-meter-second reaction wheels
SAR antenna deployment mechanism
Phased array antenna with dual polarization
The satellite is equipped with an advanced ‘active phased array'
antenna. Instead of a single device generating the microwave signals,
the antenna has a large number of modules that collectively produce the
radar beam. By suitably adjusting the signals generated by various
modules, the beam can be electronically moved around. Even if a few
modules fail, the satellite can continue to function albeit perhaps with
some degradation in performance.
With RISAT-1, ISRO scientists and engineers have demonstrated their
mastery of that difficult and closely guarded technology. If the
satellite works as its creators hope, it will match and perhaps in some
respects even surpass Canada's second-generation RADARSAT-2 that is now
The satellite cost Rs 378 crore while PSLV cost Rs 110 crore. RISAT – 1
launch has put India in the elite club of US, Canada and countries in