The NASA-ISRO Synthetic Aperture Radar (NISAR) is a joint Earth-observation mission developed by the United States’ National Aeronautics and Space Administration (NASA) and the Indian Space Research Organisation (ISRO). It represents one of the most advanced and expensive civilian Earth-observing satellites ever built. Launched successfully on July 30, 2025, from the Satish Dhawan Space Centre (SDSC SHAR) in Sriharikota, Andhra Pradesh, the mission entered its full science operations phase in January 2026.
Core Scientific Objectives
- Tracking Ecosystem Disturbances: The satellite quantifies changes in Earth’s forest biomass, agricultural areas, wetlands, and permafrost to understand carbon cycles and ecological health.
- Monitoring Ice Sheets and Cryosphere: It measures the flow rates of glaciers, ice sheet melting patterns in Antarctica and Greenland, and sea ice dynamics to study sea-level rise.
- Assessing Natural Hazards: The mission maps surface deformations caused by earthquakes, volcanic eruptions, landslides, and tsunamis to aid risk mitigation and disaster response.
- Mapping Groundwater and Soil Moisture: It tracks subtle shifts in land surfaces caused by groundwater extraction and measures regional soil moisture dynamics for agricultural planning.
Technical Specifications and Launch Details
| Parameter | Specifications and Details |
| Launch Date | July 30, 2025 |
| Launch Vehicle | ISRO’s Geosynchronous Satellite Launch Vehicle (GSLV-F16) |
| Orbit Type | Sun-Synchronous Polar Orbit (Dawn-to-Dusk type) |
| Orbital Altitude | Approximately 747 kilometers |
| Orbital Inclination | 98.4 degrees |
| Total Spacecraft Mass | 2,392 kilograms |
| Temporal Resolution | 12-day exact repeat cycle (scans the entire globe every 12 days) |
| Swath Width | 242 kilometers |
| Planned Mission Life | 5 years |
Key Technologies and Payload Architecture
- Dual-Frequency Radar Integration: NISAR is the first satellite mission to utilize two different radar frequencies simultaneously to capture ultra-high-resolution surface variations down to less than a centimeter.
- L-Band Synthetic Aperture Radar: Provided by NASA’s Jet Propulsion Laboratory (JPL), this radar operates at a wavelength of 24 centimeters, allowing it to penetrate heavy forest canopies to map underlying structural biomass.
- S-Band Synthetic Aperture Radar: Fabricated by ISRO, this radar operates at a shorter wavelength of 9.4 centimeters, making it highly sensitive to light vegetation, crop categorization, and surface soil moisture.
- Unfurlable Mesh Reflector Antenna: The satellite uses a shared 12-meter-wide wire-mesh reflector antenna provided by NASA, deployed via a long boom to focus both L-band and S-band radar signals.
- SweepSAR Technology: This specialized radar technique allows the satellite to capture a wide geographic swath (242 km) while maintaining high spatial resolution (3 to 10 meters), overcoming traditional radar imaging trade-offs.
- Spacecraft Bus: The instruments are integrated into a modified I-3K satellite bus developed by ISRO, capable of delivering 6,500 watts of power via its solar arrays.
Civil and Strategic Applications
- Agricultural Management: Regular 12-day tracking assists in estimating crop acreage, predicting crop yields, and mapping soil moisture across regional agricultural zones like the Indo-Gangetic plains.
- Disaster Mitigation and Response: The satellite provides near-real-time data during emergencies, enabling rapid assessment of damage caused by floods, cyclones, forest fires, and structural collapses.
- Geospatial and Infrastructure Monitoring: Infrastructure authorities track millimeter-level land subsidence, sinkhole formation, and structural shifts in urban centers, dams, and highways.
- Coastal Zone Mapping: The S-band radar assists India in tracking shoreline erosion, mangrove degradation, and classifying marine oil spills along its extensive coastline.
Strategic Significance for UPSC Aspirants
- Milestone for GSLV: The launch marks the first time ISRO utilized its GSLV rocket to place a payload directly into a Sun-synchronous polar orbit, showcasing enhanced launch vehicle flexibility.
- Data Democratization: All scientific data generated by the L-band and S-band radars are uploaded to open-access portals like NASA’s Alaska Satellite Facility and ISRO’s Bhoonidhi portal within one to two days of collection.
- Bilateral Synergy: The project sets a global benchmark for Indo-US strategic and scientific cooperation, moving from standalone space exploration toward heavily integrated deep-tech collaboration.