Key Terms & Concepts — UPSC Mains
NISAR (NASA-ISRO Synthetic Aperture Radar)
"Joint NASA-ISRO Earth-observation satellite, the world's first dual-frequency radar imaging satellite, launched July 30, 2025 and fully operational by January 2026."
NISAR is a joint Earth-observation mission by NASA and ISRO and the first satellite to carry dual-frequency synthetic aperture radar (NASA's L-band and ISRO's S-band). It was launched on July 30, 2025, aboard a GSLV Mk-II from Satish Dhawan Space Centre, Sriharikota. NISAR maps nearly all of Earth's land and ice surfaces every 12 days at 5 to 10 metre resolution, regardless of cloud cover or daylight. It was commissioned into service on November 7, 2025, and declared fully operational in January 2026, with a mission life of three years for the NASA L-band baseline and five years for ISRO's S-band operations. It tracks crustal deformation, glacier and ice-sheet change, groundwater movement, deforestation and natural hazards.
GS3 (science and technology, space, disaster management). Prelims: dual-frequency L-band (NASA) and S-band (ISRO) radar, GSLV Mk-II launch, 12-day repeat cycle. Mains: India-US space cooperation; SAR applications for agriculture, disaster early warning and climate monitoring.
- 1 First satellite with dual-frequency (L-band plus S-band) synthetic aperture radar
- 2 Launched July 30, 2025, on GSLV Mk-II from Sriharikota
- 3 Among the most expensive Earth-imaging satellites built (over USD 1.5 billion)
- 4 NASA provides the L-band radar; ISRO the S-band radar and the launch
- 5 12-metre drum-shaped deployable mesh reflector antenna
- 6 Repeat coverage every 12 days; resolution 5 to 10 metres
- 7 Commissioned November 7, 2025; fully operational January 2026
- 8 Data released freely; 100,000+ products by February 2026
- 9 Mission life: 3 years (NASA baseline); 5 years (ISRO S-band)
- 10 Applications: earthquakes, landslides, subsidence, glaciers, soil moisture, biomass
By early 2026, NISAR data was enabling Indian agencies to monitor land subsidence and Himalayan glacier melt with all-weather radar precision.
