NISAR satellite enhances global Earth observation efforts

Source: The post NISAR satellite enhances global Earth observation efforts has been created, based on the article “NISAR’s two eyes on Earth” published in “Indian Express” on 30th July 2025

UPSC Syllabus Topic: GS Paper 3 – Science and Technology-  Awareness in the fields of Space

Context: India and the United States are set to launch a unique Earth observation satellite called NISAR. Jointly developed by ISRO and NASA after over a decade of collaboration, NISAR will become the most advanced radar satellite ever sent into orbit, capable of delivering unprecedented data across environmental and geophysical domains.

For detailed information on NISAR Satellite read this article here

Unique Capabilities of NISAR

1. A Technological Milestone: NISAR is the first satellite to carry two Synthetic Aperture Radars (SARs) operating in L-band and S-band frequencies. This allows it to capture highly detailed images of Earth’s surface features.
2. Record-Breaking Cost and Power: With a budget exceeding $1 billion, NISAR is the most expensive Earth observation satellite ever developed. It will produce high-resolution data across terrains and conditions, surpassing existing satellite capabilities.
3. Advanced Antenna Design: Its 12-metre diameter antenna mimics a 20-km ground-based radar, achieving exceptional resolution through advanced space-based radar technology.

Understanding Synthetic Aperture Radars (SARs)

1. Functionality of SARs: SARs send microwave or radio signals toward Earth and analyse reflected signals to determine object distance, movement, composition, and texture. They simulate large radars using small space-compatible equipment.
2. Space Optimization: Unlike bulky dish radars used on Earth, SARs use algorithms to replicate similar performance in space. This makes them ideal for satellite use.
3. SARs in Other Missions: ISRO has used SARs in its RISAT series, now renamed EOS, but those satellites use only one SAR. Other ISRO satellites like Cartosat and Oceansat do not use SARs.

Benefits of Dual-Band SAR Imaging

1. Complementary Frequency Use: The L-band SAR penetrates vegetation, ice, and sand to detect surface variations and biomass. The S-band SAR captures broader features like crops and water bodies.
2. All-Weather, All-Time Observation: Both SARs operate through clouds, fog, rain, and darkness. This ensures uninterrupted observation of Earth’s surface in any condition.
3. Synchronized Imaging for Accuracy: By combining both SARs on the same satellite, NISAR captures simultaneous images of a location, avoiding time gaps that separate satellites would cause.
4. Engineering Innovation: Installing two SARs required customized hardware and non-interfering signal systems, resulting in extended development time and high complexity.

Significance of the NASA-ISRO Partnership

1. Division of Roles and Investment: NASA contributed the L-band SAR, antenna, GPS systems, and invested $1.16 billion. ISRO provided the S-band radar, spacecraft, launch vehicle, and $90 million.
2. Joint Operations and Legacy: Both agencies will operate the mission from their ground stations. Though they collaborated earlier on Chandrayaan-1, NISAR is their first jointly developed mission.
3. Growing Strategic Cooperation: The mission strengthens US-India space ties, supported by India’s inclusion in the Artemis Accords and ongoing joint efforts in human spaceflight.

Scientific Applications and Global Relevance

1. Mission Origins: NISAR was envisioned after a 2007 US report recommended monitoring changes in land, ice, and vegetation. NASA initiated the mission in 2008, with ISRO joining in 2012.
2. Diverse Research Goals: NISAR will aid studies on climate change, surface deformation, volcanic activity, biomass, and crop cycles, delivering critical environmental insights.
3. Global Data for Policymaking: With unmatched imaging capabilities, NISAR will benefit global scientists and decision-makers addressing ecological and geological challenges.

Question for practice:

Discuss how the NISAR mission showcases technological innovation and international collaboration in Earth observation.