What Happened
- ISRO announced that the NASA-ISRO Synthetic Aperture Radar (NISAR) satellite is now generating 100-metre resolution soil moisture data across India with a repeat cycle of 12-13 days.
- The Level-4 operational soil moisture products, generated twice every 12 days, are being systematically produced at the National Remote Sensing Centre (NRSC) under the IMGEOS facility.
- The data will be disseminated through the Bhoonidhi Portal, ensuring access for farmers, planners, researchers, government agencies, and non-government entities across the country.
- The soil moisture products have been demonstrated using both S-band and L-band data, providing consistent estimates across India's diverse agro-climatic regions including irrigated plains, rainfed farmlands, semi-arid zones, and high-rainfall areas.
- Fully calibrated global data products are anticipated for release around May-June 2026.
Static Topic Bridges
NASA-ISRO Synthetic Aperture Radar (NISAR) Mission
NISAR is a joint Earth observation mission between NASA and ISRO, making it the first radar imaging satellite to use dual-frequency Synthetic Aperture Radar (SAR). It was launched aboard a GSLV rocket on 30 July 2025 from Sriharikota. The satellite was officially commissioned into scientific service on 7 November 2025 and declared fully operational in January 2026. With a total cost estimated at approximately US$1.5 billion, it is considered one of the most expensive Earth-imaging satellites ever built.
- Operates in two microwave bands: L-band (24 cm wavelength, provided by NASA) and S-band (10 cm wavelength, provided by ISRO)
- Uses a 12-metre deployable mesh antenna and SweepSAR scan-on-receive wide-swath mapping technology
- Spacecraft mass: approximately 2,800 kg
- Orbital repeat cycle: 12 days, sampling Earth on average every 6 days (ascending and descending passes)
- Baseline mission duration: 3 years
- NASA provided: L-band SAR, high-rate telecom subsystem, GPS receivers, solid-state recorder, payload data subsystem
- ISRO provided: satellite bus, S-band SAR, GSLV launch vehicle, and launch services
Connection to this news: The 100-metre soil moisture products represent one of NISAR's first major operational outputs, demonstrating the mission's practical application for Indian agriculture and water resource management using its dual-frequency SAR capability.
Synthetic Aperture Radar (SAR) Technology
SAR is an active remote sensing technology where the instrument transmits microwave pulses toward Earth's surface and records the reflected energy. Unlike optical sensors, SAR can operate day and night, in all weather conditions, and can penetrate cloud cover, making it critical for monitoring regions with persistent cloud cover such as India during monsoon season.
- L-band SAR (wavelength ~23 cm): Penetrates deeper through tree canopies, interacts with large branches and trunks; ideal for biomass estimation, surface deformation, and soil moisture retrieval at deeper levels
- S-band SAR (wavelength ~12 cm): Better at quantifying changes in tree canopy height and melting snowpack; intermediate penetration
- C-band SAR (wavelength ~5 cm): Used by ESA's Sentinel-1; better for surface-level observations
- SAR applications include: land subsidence monitoring, earthquake and volcanic activity detection, flood mapping, glacier movement tracking, forest biomass estimation, and agricultural monitoring
- Interferometric SAR (InSAR): Technique using two SAR images to detect ground displacement at millimetre scale
- Resolution in SAR depends on the "synthetic aperture" created by the satellite's motion, not physical antenna size
Connection to this news: NISAR's dual-frequency SAR enables soil moisture retrieval at unprecedented 100-metre resolution by using a physics-based algorithm developed at ISRO's Space Applications Centre (SAC), which leverages both L-band and S-band signals to estimate moisture at different soil depths.
Bhoonidhi Portal and India's Earth Observation Data Ecosystem
Bhoonidhi is ISRO's Earth Observation (EO) data hub operated by the National Remote Sensing Centre (NRSC). It serves as a single-window platform for the dissemination of satellite data products, hosting imagery from over 44 satellites including both Indian and international remote sensing missions. The portal enables users to search, view, and download raw and processed satellite data.
- Operated by NRSC, Department of Space, Government of India
- Hosts data from ISRO missions (Resourcesat, Cartosat, Oceansat, RISAT, etc.) and partner missions
- Provides both open-access and priced data products through a web-based interface
- Bhoonidhi API has been released for programmatic satellite data access
- Complemented by Bhuvan portal (ISRO's geospatial platform for thematic maps and visualization)
- NISAR soil moisture products will be operationally disseminated through Bhoonidhi
Connection to this news: NISAR's 100-metre soil moisture data will be made accessible through Bhoonidhi, representing a major expansion of the portal's agricultural data offerings and enabling wide-scale access for Indian farmers, researchers, and policy planners.
Soil Moisture Monitoring and Agricultural Drought Assessment in India
Soil moisture is a critical indicator for crop health assessment, irrigation scheduling, and drought risk monitoring. India's institutional framework for agricultural drought assessment centres on the National Agricultural Drought Assessment and Monitoring System (NADAMS), developed by NRSC and operationalized by the Mahalanobis National Crop Forecast Centre (MNCFC), established on 23 April 2012 under the Ministry of Agriculture and Farmers' Welfare.
- NADAMS covers 17 states and uses satellite-derived vegetation indices (NDVI), rainfall data, and soil moisture indices for drought assessment during Kharif season
- MNCFC uses both optical and microwave remote sensing for crop acreage estimation, crop condition assessment, and production forecasting
- Prior to NISAR, soil moisture data was primarily derived from SMOS (ESA), SMAP (NASA), and microwave radiometers with coarser resolution (~25-40 km)
- NISAR's 100-metre resolution represents a quantum leap over the existing ~25-40 km resolution data, enabling field-level monitoring
- India's agriculture is particularly dependent on monsoon-driven soil moisture, with approximately 52% of net sown area being rainfed
Connection to this news: NISAR's 100-metre resolution soil moisture data every 12-13 days will dramatically enhance India's agricultural monitoring capability, providing field-level precision that was previously unavailable from satellite sources, thereby strengthening both NADAMS drought assessment and crop forecasting under MNCFC.
Key Facts & Data
- NISAR launched: 30 July 2025; commissioned: 7 November 2025; fully operational: January 2026
- Resolution of soil moisture products: 100 metres (compared to previous ~25-40 km from SMAP/SMOS)
- Repeat cycle: 12 days; data generated twice every 12 days
- Dual-frequency: L-band (24 cm, NASA) and S-band (10 cm, ISRO)
- Mission cost: approximately US$1.5 billion (joint)
- Antenna diameter: 12 metres (deployable mesh)
- Dissemination portal: Bhoonidhi (NRSC)
- Algorithm developed at: Space Applications Centre (SAC), ISRO
- Global calibrated data release expected: May-June 2026