RAS question
RISAT-1, India's first indigenous all-weather radar imaging satellite, uses which type of radar?
Correct answer: (D) C-band SAR.
RISAT-1 used a C-band Synthetic Aperture Radar payload operating at 5.35 GHz for all-weather, day-and-night surface imaging.
Explanation
RISAT-1 was India's Radar Satellite-1, launched by PSLV-C19 on April 26, 2012, and its key payload was a Synthetic Aperture Radar operating in the C-band at 5.35 GHz. ISRO describes RISAT-1 as a microwave remote-sensing mission whose C-band SAR could image surface features during both day and night and under all weather conditions. Active microwave remote sensing can penetrate cloud cover, so RISAT-1 supported applications such as agriculture, especially paddy monitoring in the kharif season, and disaster management for events such as floods and cyclones.
Why the other options are wrong
- (A) RISAT-1 did not use L-band SAR; NISAR uses L-band radar, while ISRO identifies RISAT-1's payload as C-band SAR.
- (B) RISAT-1 did not use S-band SAR, and ISRO specifies C-band at 5.35 GHz instead.
- (C) The RISAT-2 series is associated with X-band SAR, whereas RISAT-1 carried a C-band Synthetic Aperture Radar.
Concept
Space technology within remote sensing connects satellite missions with sensor types and operating bands. In RAS preparation, radar imaging, agriculture monitoring and disaster management link Science and Technology with governance applications.