Context

• The NASA - ISRO Synthetic Aperture Radar(NISAR) was successfully launched from Satish Dhawan Space Centre at Sri-Harikota in Andhra Pradesh.

About NISAR Satellite

• NISAR is an Earth-observation satellite that stands for NASA-ISRO Synthetic Aperture Radar.
• It is Jointly developed by the National Aeronautics and Space Administration (NASA) and the Indian Space Research Organisation under a partnership agreement signed in 2014.
• It will be launched into a polar Sun-synchronous dawn-dusk orbit at 747 km altitude and an inclination of 98.4º.
• NISAR is the first satellite mission to collect radar data in two microwave bandwidth regions, called the L-band and the S-band.
• The S-band payload has been made by the ISRO and the L-band payload by the U.S. 

Application of NISAR satellite

• Solid Earth Processes – Tracking earthquakes, landslides, and land deformation.
• Ecosystems – Monitoring forests, woody biomass, and biodiversity.
• Ice and Snow Dynamics – Measuring glacial movements and polar ice thickness.
• Coastal and Ocean Monitoring – Tracking shoreline erosion, oil spills, and storm surges.
• Disaster Response – Providing near-real-time damage maps after floods, quakes, or cyclones.
• Agriculture and Infrastructure – Supporting food security and monitoring subsidence near dams, roads, and reservoirs.

Working of NISAR

• NISAR combines two types of Synthetic Aperture Radar (SAR) systems:
  • The L-band SAR (1.257 GHz) uses longer-wavelength radio waves that can penetrate thick vegetation and even soil, making it ideal for observing ground deformation beneath forests.
  • The S-band SAR (3.2 GHz) uses shorter-wavelength radio waves that are more effective at detecting surface details such as crops, water surfaces, and urban infrastructure.
• The satellite also uses polarimetric radar technology, which involves sending and receiving radar signals in both horizontal and vertical polarizations.
  • Satellite operations and commanding will be managed by ISRO, while NASA will provide the orbit maneuver plan and radar operations plan. 

Objectives of the Mission

• NISAR can measure tectonic plate movements accurately. So a lot of geological, agricultural and water-related observations can be obtained from this satellite.
• It can study the water-stressing, climate change-related issues, agricultural changes through patterns, yield, desertification and continental movements precisely with respect to annual water cycle movements. 
• NISAR’s data can help people worldwide better manage natural resources and hazards, as well as providing information for scientists to better understand the effects and pace of climate change. 

India - USA Contributions

• ISRO contributed the spacecraft bus, the entire S-band radar system, Ka-band telemetry systems, and launch support via GSLV Mk-II.
• NASA provided the L-band radar, radar structure, antenna, onboard avionics, and high-capacity data systems.

About Geosynchronous Satellite Launch Vehicle (GSLV)

• GSLV is larger and more powerful than ISRO's Polar Satellite Launch Vehicle (PSLV). 
• GSLV-F16 is the 18th launch of India's GSLV and 12th launch using India's cryogenic upper stage, which helps carry heavier satellites. 
• The rocket used a 4-metre wide, dome-shaped (ogive) nose cone to protect the NISAR satellite during launch. 
• This is the first time a GSLV rocket has placed a satellite (NISAR) into a Synchronous Polar Orbit, instead of its usual Geosynchronous Transfer Orbit.