NISAR: The NASA-ISRO Satellite That Will Revolutionize Earth Observation

1. What is context?

In a world increasingly affected by natural disasters, climate change, and environmental degradation, timely and accurate data on Earth’s surface has become essential. The NASA-ISRO Synthetic Aperture Radar (NISAR) satellite is a landmark initiative in this direction. As one of the most advanced Earth observation satellites ever built, NISAR is poised to redefine how we monitor, manage, and mitigate environmental risks and natural hazards.

For UPSC aspirants, particularly those preparing for the Mains examination, understanding the significance of NISAR offers valuable insights into topics such as disaster management, technological advancements in space, environmental governance, and India-US scientific collaboration.

2. What is NISAR?

NISAR is the first major Earth-observing satellite that will use dual-frequency synthetic aperture radar (SAR)—operating in both L-band and S-band—to map the Earth’s surface with unprecedented detail. It is a joint collaboration between India’s ISRO (Indian Space Research Organisation) and the United States’ NASA (National Aeronautics and Space Administration).

Scheduled for launch from Sriharikota on July 30, 2025 aboard a GSLV Mk II rocket, NISAR will be positioned in a near-polar sun-synchronous orbit, enabling it to scan almost the entire globe every 12 days.

3. Why is NISAR important?

A. Dual-Band Radar Technology

Most Earth-observing satellites operate with single-band radar, limiting their ability to penetrate clouds, smoke, vegetation, or darkness. NISAR’s dual-band (L-band by NASA and S-band by ISRO) capability allows it to overcome these limitations, making it effective in all weather conditions and during both day and night.

This ensures consistent, high-quality observations for:

Earthquake monitoring
Glacier movements
Forest biomass estimation
Soil moisture analysis
Urban mapping
Crop monitoring
Flood and landslide prediction

B. Unparalleled Resolution and Coverage

NISAR will orbit at 747 km altitude and image the same spot every 12 days. Its wide swath of 240 km and high-resolution imaging will help generate detailed, large-scale maps of Earth’s dynamic surface processes, including tectonic shifts, forest growth, and polar ice movement.

This is a critical tool for climate scientists and policymakers, especially in the era of rapid environmental change.

4. Applications in the Indian Context

A. Agriculture and Food Security

India’s dependence on monsoon and agriculture makes it highly vulnerable to droughts and floods. NISAR will help assess:

Soil moisture conditions
Crop sowing area
Crop health and yield
Land use changes

These insights will enable better implementation of schemes like PM Fasal Bima Yojana and optimize agricultural subsidies.

B. Disaster Management

Real-time imaging and early detection of natural hazards such as:

Earthquakes
Landslides
Floods
Cyclones

It can drastically reduce response times and improve coordination under the National Disaster Management Plan. During disasters, NISAR can even re-orient to capture data from priority zones within hours.

C. Climate Change and Environmental Monitoring

India is part of several international climate commitments, including the Paris Agreement. NISAR will support India’s INDCs (Intended Nationally Determined Contributions) by providing valuable data for:

Carbon stock estimation in forests
Glacier and sea-level changes
Coastal erosion monitoring

D. Urban Planning and Infrastructure

NISAR’s precise imaging can help urban authorities in:

Monitoring illegal encroachments
Land subsidence in urban zones
Infrastructure development in earthquake-prone areas

5. How will NISAR collect and deliver data?

NISAR uses a synthetic aperture radar (SAR) to emit microwave pulses toward the Earth and receive echoes. Unlike optical imaging, SAR can penetrate clouds and work at night. It produces extremely detailed data by simulating a large antenna through signal processing techniques.

Data will be processed by ISRO’s Space Applications Centre and NASA’s Jet Propulsion Laboratory (JPL). Importantly, data products from NISAR will be made freely available to scientists and the public within hours, promoting transparency and scientific collaboration.

6. How was NISAR built?

NISAR represents a unique fusion of technological expertise from India and the US. While NASA built the L-band radar system, ISRO provided the satellite bus and S-band radar. Key institutions involved:

NASA’s Jet Propulsion Laboratory (JPL): Responsible for L-band radar, reflector antenna, and radar electronics.
ISRO’s U R Rao Satellite Centre (URSC): Built the spacecraft and integrated S-band radar.
Space Applications Centre (SAC): Designed S-band electronics.
Other contributors: Agencies in Italy, Norway, the UK, and Japan provided critical parts.

The radar payload itself is massive—comprising a 12-meter deployable mesh reflector that unfolds once the satellite is in orbit. This makes NISAR the largest radar imaging satellite ever built.

7. Significance for UPSC Aspirants

A. GS Paper 1 – Geography

NISAR’s data will enhance understanding of geomorphological processes like landslides, earthquakes, and glacial movements.
Relevance in topics like “Distribution of key natural resources,” “Changes in critical geographical features,” etc.

B. GS Paper 3 – Disaster Management

Case studies on how remote sensing improves disaster preparedness and early warning systems.
Role in mitigating the impact of natural hazards in vulnerable regions.

C. GS Paper 3 – Science and Technology

Importance of international collaborations in space research.
Indigenous capacity building in advanced radar and satellite technologies.

8. Challenges and considerations

Despite its potential, NISAR’s implementation will need:

Capacity building in state-level agencies to interpret and use satellite data.
Infrastructure to disseminate real-time alerts to rural populations.
Clear policies on data usage and privacy.

9. Conclusion

NISAR is not just a scientific project—it is a strategic tool for sustainable development. It embodies the power of Indo-US cooperation in addressing global challenges like climate change, food security, and disaster resilience. For India, especially, it could become a key enabler in transforming data-driven policy decisions.

For UPSC aspirants, NISAR offers a model example of how technology, diplomacy, and sustainability intersect—making it a perfect case study across several GS papers and essays.