India and the United States are set to launch their first joint Earth observation satellite — the Nasa-Isro Synthetic Aperture Radar (Nisar).

The satellite will be launched on July 30, 2025, at 17:40 IST.

The historic mission marks a new era of collaboration, harnessing the collective expertise of the Indian Space Research Organisation (Isro) and Nasa to revolutionise the study of Earth’s dynamic surface.

WHAT IS NISAR MISSION?

The Nisar satellite, with a mass of 2,392 kg, will be launched aboard Isro’s GSLV-F16 rocket from the Satish Dhawan Space Centre (SDSC SHAR) in Sriharikota.

The launch vehicle will deploy Nisar into a 743 km sun-synchronous orbit with an inclination of 98.40. This unique orbit favours continuous, consistent illumination, ideal for systematic Earth monitoring.

Nisar will be the world’s first satellite to operate a dual-frequency Synthetic Aperture Radar (SAR), combining Nasa’s L-band and Isro’s S-band radars.

Mounted on a sophisticated 12 m unfurlable mesh reflector and integrated with Isro’s modified I3K satellite bus, this pioneering payload leverages “SweepSAR” technology—making high-resolution, wide-swath Earth imaging possible for the first time at this scale.

HOW IT IS DIFFERENT

L-band Radar (Nasa): Longer wavelengths penetrate vegetation, soil, and even ice, enabling detailed tracking of soil moisture, forest biomass, ice sheet thickness, and subsurface features.

S-band Radar (Isro): Shorter wavelengths make the S-band highly sensitive to surface characteristics—useful for detecting crop structures, snow cover, and fine surface deformations.

Together, these sensors deliver comprehensive, all-weather, day-and-night data at a 12-day repeat interval, with imaging resolutions between 5 and 10 meters and a swath width of 242 km.

FROM SCIENCE TO DISASTER RELIEF

Nisar is designed to observe and quantify some of the planet’s most critical natural phenomena, including:

• Ground Deformation: Monitor earthquakes, volcanoes, and landslides by detecting even centimeter-scale changes in the Earth’s crust.
• Ice and Glaciers: Track movement and melting of polar ice sheets—a crucial input for climate models.
• Ecosystem Monitoring: Assess changes in forest cover, crop growth, and vegetation dynamics for sustainable agriculture.
• Hydrology: Track soil moisture, surface water bodies, and changes in wetlands that are vital for water resource management.
• Disaster Response: Provide real-time data to support relief operations after cyclones, tsunamis, floods, and wildfires.
• Coastal and Maritime Surveillance: Monitor coastal erosion, sea ice, and marine traffic for enhanced security and environmental protection.

Global Impact

The Nisar mission marks a paradigm shift in international space cooperation. By pooling resources and complementary radar technologies, Isro and Nasa aim to deliver unprecedented insights into Earth’s evolving landscapes.

The mission’s comprehensive data streams will empower governments, researchers, and disaster-response teams across the globe, aiding informed decision-making in areas such as food security, environmental protection, urban planning, and climate change mitigation.

(With inputs from Kumar Kunal)

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