Why in the News?

• The Indian Space Research Organisation (ISRO) is planning to launch the NISAR satellite from Sriharikota onboard a GSLV Mk-II rocket.

What’s in Today’s Article?

• NISAR (Introduction, Features & Capabilities, Applications, India-specific enhancements, Individual Contributions, etc.)

Introduction

• India and the United States are set to launch their most ambitious joint space mission to date, the NASA-ISRO Synthetic Aperture Radar (NISAR)
• Scheduled for lift-off on July 30 from Sriharikota onboard a GSLV Mk-II, the Rs. 12,000-crore mission has been over a decade in the making and is being considered as one of the world’s most advanced Earth observation missions.
• NISAR will provide real-time, high-resolution radar data on land deformation, biomass, disaster impact, crop patterns, and climate-related changes, not just for India but globally.
• It combines NASA’s strength in long-range radar systems with ISRO’s spaceflight engineering and S-band radar technology.

Unique Features and Capabilities of NISAR

• First Dual-Band Radar Satellite for Earth Observation
  • NISAR is the world’s first Earth-observing satellite with dual-frequency synthetic aperture radar (SAR).

• L-band radar (1.257 GHz) from NASA can penetrate dense forests and soil layers to detect ground deformation and subsurface movement.
• S-band radar (3.2 GHz) from ISRO is optimised for surface-level changes like crop growth, biomass estimates, and water levels.
• This dual-frequency advantage allows for all-weather, day-and-night imaging, even through clouds, smoke, or vegetation cover.

• Wide Swath and High Resolution

• NISAR’s radar swath width is 240 km, allowing it to scan large areas in one go.
• It offers a spatial resolution of 3-10 metres and vertical displacement mapping accuracy down to centimetres, enabling early detection of phenomena like land subsidence in cities.
• Every spot on Earth will be revisited once every 12 days, providing consistent monitoring.

Scientific and Societal Applications

• NISAR is designed to support research and operations across six broad themes:

• 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.

• During natural disasters, NISAR can provide damage proxy maps within five hours, crucial for emergency relief planning and response.

India-Specific Enhancements

• While NISAR will operate globally at the L-band, ISRO will routinely operate the S-band radar over Indian territory, enabling:

• Enhanced biomass and soil moisture mapping
• Improved agricultural forecasting
• Ionospheric noise correction for high-precision imagery

• All of this aligns with India’s national needs in agriculture, disaster management, forestry, and rural development.

Technical Design and Deployment

• Once launched, NISAR will be placed in a sun-synchronous polar orbit at an altitude of 747 km.
• It features a massive 12-metre mesh radar antenna and a 9-metre boom to support deployment and scanning.
• To overcome size constraints in space, the SAR system mimics a large antenna by collecting radar pulses over time and combining them through complex processing, hence the term “synthetic aperture.”
• Its advanced SweepSAR mode allows electronic steering of radar beams, providing consistent swath coverage without compromising resolution.

Data Access and Ground Infrastructure

• NISAR’s open-data policy ensures that data is freely available to all users, typically within a few hours of acquisition.

• NASA’s Near Earth Network (in Alaska, Norway, and Chile) will handle most global data downlinks (up to 3 TB/day).
• ISRO’s Ground Stations in Shadnagar and Antarctica will manage India’s data needs.
• India’s National Remote Sensing Centre (NRSC) will process and distribute NISAR products for domestic use.

India-U.S. Contributions

• The mission exemplifies balanced international collaboration:

• 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.

• The satellite was integrated and tested in Bengaluru, symbolising “Made-in-India” ownership of a global science instrument.