India's own imaging radar, built by ISRO, which sees the ground through cloud and at night. It flew on RISAT-1 and flies on EOS-04.
A synthetic aperture radar (SAR) sends its own microwave pulses and records the echoes. It does not need sunlight, and microwaves pass through cloud. So it can image the ground day and night in any weather. Wet soil, flooded fields and rough surfaces echo differently, which makes radar useful for crops and floods.
The radar uses a flat, electronically steered antenna about 6.3 m long, built from many small active tiles. It folds in three panels for launch and opens in orbit. By steering its beam electronically and tilting the spacecraft, it can image strips from about 10 km to 225 km wide at resolutions from about 1 m to 50 m. Higher detail means a narrower strip.
PSLV-C19 launched RISAT-1 in April 2012. ISRO highlights its use for monitoring kharif paddy, which grows in the cloudy monsoon season, and for floods and cyclones. EOS-04 (also called RISAT-1A), launched by PSLV-C52 in February 2022, carries a C-band SAR to continue this work for agriculture, forestry, soil moisture and flood mapping.