RISAT-1 was India's first radar imaging satellite, able to photograph the ground by day or night through cloud. PSLV-C19 launched it in April 2012; it was decommissioned in 2017.
No longer operational, according to the public satellite catalogue.
RISAT-1 carried a C-band synthetic aperture radar working at 5.35 GHz. Radar sends out its own microwaves, so it can image the surface in darkness and through cloud. That made it useful for watching paddy fields in the cloudy kharif season and for mapping floods and cyclone damage.
At 1,858 kg it was the heaviest satellite PSLV had launched up to then. A solar array gave 2,200 W, with a 70 ampere-hour nickel-hydrogen battery. It flew in a sun-synchronous polar orbit about 536 km up, crossing the equator at 6 am and 6 pm and repeating its ground track every 25 days.
PSLV-C19, the twenty-first PSLV flight, launched it from Sriharikota in April 2012. It was the third flight of the PSLV-XL version, after Chandrayaan-1 and GSAT-12.
RISAT-1 was designed for five years. It was decommissioned and declared non-operational in 2017. RISAT-1A (EOS-04) was later launched to continue its work.