NISAR SATELLITE
Context:
- The NASA-ISRO Synthetic Aperture Radar (NISAR) satellite was successfully launched on July 30, 2025, at 5:40 p.m. IST, aboard India’s Geosynchronous Satellite Launch Vehicle (GSLV-F16) from the 2nd launch pad of the Satish Dhawan Space Centre in Sriharikota.
- This joint mission between NASA (U.S.) and ISRO (India) marks a landmark achievement in international space cooperation for Earth observation.
ABOUT NISAR MISSION
- Full Form: NASA-ISRO Synthetic Aperture Radar (NISAR).
- Collaboration: A joint mission between the National Aeronautics and Space Administration (NASA) of the U.S. and the Indian Space Research Organisation (ISRO). It represents the first major Earth observation satellite co-developed by the two agencies.
- Launch Vehicle: Launched by ISRO’s GSLV-F16 rocket. This is also notable as it marks the first time a GSLV has placed a satellite into a sun-synchronous polar orbit.
- Orbit: The GSLV-F16 injected the 2,392 kg NISAR satellite into a 743-km sun-synchronous orbit.
- This orbit allows the satellite to always view Earth under consistent lighting conditions, crucial for accurate data comparison over time.
- Mission Life: The NISAR mission has a planned life of five years.
UNIQUE FEATURES
- Dual-Frequency Synthetic Aperture Radar (SAR):
- NISAR is the first satellite to observe Earth with a dual-frequency Synthetic Aperture Radar (SAR).
- NASA provides the L-band radar (wavelength of ~24 cm), which is adept at penetrating dense vegetation and monitoring soil moisture, forest biomass, and the motion of land and ice surfaces.
- ISRO provides the S-band radar (wavelength of ~9 cm), optimized for high-resolution imaging of agricultural land, urban infrastructure, and coastal regions.
- Both radar systems utilize NASA’s 12-meter unfurlable mesh reflector antenna, integrated with ISRO’s modified I3K satellite bus.
- The dual-band capability allows NISAR to penetrate through clouds, fog, and even light rain, providing all-weather, day-and-night data.
SWEEPSAR TECHNOLOGY
- NISAR utilizes SweepSAR technology for the first time in space.
- This advanced radar technique allows the satellite to achieve a wide swath of 242 km (area covered on the ground) while maintaining high spatial resolution.
- SweepSAR works by having the radar’s signal feed sweep its beam across the antenna’s reflector as it receives echoes, effectively expanding the area the radar can “listen” to and process.
APPLICATIONS & DATA COLLECTION
- Global Coverage: The satellite will scan the entire globe and provide all-weather, day-and-night data at 12-day intervals.
- In emergency situations like natural disasters, data can be available within hours.
- High Sensitivity: NISAR can detect even small changes in Earth’s surface, down to fractions of an inch (centimeter-level precision).
WIDE RANGE OF APPLICATIONS
- Climate Change Monitoring: Measuring glacier retreat, ice sheet movement, deforestation, and carbon storage changes.
- It will provide vital input to climate models.
- Natural Disaster Management: Early detection and monitoring of ground deformation (e.g., from earthquakes, volcanic activity), landslides, and tsunamis.
- This will aid in disaster preparedness and response.
- Ecosystem and Biodiversity: Mapping land ecosystems, studying forest dynamics (biomass, deforestation), and wetland changes to track biodiversity and carbon storage.
- Agriculture & Resource Management: Monitoring crop growth, soil moisture changes, land use mapping, and surface water resources, which is critical for agricultural forecasting and food security.
- Oceanic Regions: Observing coastal changes, sea ice classification, ship detection, and shoreline monitoring.
- Urban Development: Monitoring land subsidence in megacities and assessing infrastructure resilience.
MISSION PHASES
The NISAR mission is broadly classified into different phases:
- Launch Phase: The satellite was successfully launched by the GSLV-F16 launch vehicle.
- Deployment Phase: In orbit, a crucial step will be the deployment of the 12-meter reflector antenna, which will unfurl nine meters away from the satellite via a complex multistage deployable boom.
- This process is expected to begin around the 10th day after launch.
- Commissioning Phase (In-orbit Checkout): The first 90 days after launch will be dedicated to commissioning, or in-orbit checkout.
- The objective is to prepare the observatory for science operations, involving initial checks and calibrations of mainframe elements, followed by payload and instrument checkout by JPL (NASA’s Jet Propulsion Laboratory).
- Science Operations Phase: This final phase begins at the end of commissioning and continues for NISAR’s five-year mission life.
- During this period, the science orbit will be maintained through regular maneuvers, and extensive calibration and validation activities will take place to ensure high-quality data collection.
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