The NASA–ISRO Synthetic Aperture Radar (NISAR) mission has entered a major operational milestone following the successful deployment of its 12-metre radar antenna reflector in orbit. Launched aboard the GSLV-F16 in July 2025, NISAR is now actively capturing high-resolution Earth observation data to support global climate and disaster response research.
Successful In-Orbit Antenna Deployment
The radar antenna — stowed compactly inside the rocket — underwent a meticulous multi-stage deployment sequence beginning 9 August 2025. Over five days, engineers executed controlled unfolding of the wrist, shoulder, elbow and root mechanisms. By 15 August, NASA and ISRO confirmed full deployment and optimal performance of the flexible, gold-mesh reflector.
This marks a major milestone in NISAR’s complex dual-band radar mission, making it one of the most advanced Earth-imaging satellites ever deployed.
First S-Band SAR Imagery: Godavari Delta
NISAR’s first S-Band Synthetic Aperture Radar (SAR) images were released on 19 August 2025, capturing the Godavari River Delta in stunning detail. The data clearly differentiated between:
- Dense mangroves
- Agricultural lands
- Aquaculture ponds
- Water-dominated zones
These initial results highlight the satellite’s capability to monitor coastal ecosystems, floodplains, and changes in vegetation and land use..
Precision Calibration for Scientific Operations
To ensure data accuracy, calibration reflectors were installed near Ahmedabad and other sites across India. Additional radar datasets were collected over the Amazon rainforest to fine-tune spacecraft alignment, pointing accuracy and signal interpretation.
With both S-Band (ISRO) and L-Band (NASA) instruments calibrated, NISAR is now ready to support mission science objectives including:
- Earthquake and landslide mapping
- Soil moisture & agricultural monitoring
- Glacier, ice-sheet and coastline movement tracking
- Forest biomass and carbon cycle studies
- Disaster early warning systems
Exam-Oriented Facts
| Feature | Details |
|---|---|
| Developers | NASA & ISRO |
| Launch Vehicle | GSLV-F16 |
| Launch Date | July 2025 |
| Antenna Reflector Size | 12 metres |
| Radar Frequencies | S-Band (ISRO) & L-Band (NASA) |
| First Image Location | Godavari Delta (19 Aug 2025) |
About NISAR Mission:
What is NISAR?
- NISAR stands for NASA-ISRO Synthetic Aperture Radar. It is a jointly developed Earth-observation mission by the Indian Space Research Organisation (ISRO) and NASA (USA).
- The mission’s goal: to systematically monitor and map changes on Earth’s surface — land, ice, vegetation, oceans — using advanced radar imaging.
- NISAR uses radar (Microwave) imaging instead of optical imaging, meaning it can “see” through clouds, rain, vegetation and can operate day and night.
Key Mission Details
| Parameter | Detail |
|---|---|
| Launch Date | July 30, 2025 (GSLV-F16 rocket, from Satish Dhawan Space Centre, Sriharikota) |
| Orbit | Sun-synchronous orbit, altitude ~ 747 km, inclination ~98.5° |
| Mission Life (nominal) | Minimum 3 years; though the bus and propellant allow longer operation. |
| Observation Frequency | Global coverage every 12 days (ascending + descending passes), effectively sampling many areas every ~6 days on average. |
| Satellite Bus / Size / Mass | Built on ISRO’s I-3K platform; mass approx. 2,392–2,800 kg. |
Payloads and Technology
The core strength of NISAR lies in its dual-frequency Synthetic Aperture Radar (SAR) payloads:
- L-band SAR (provided by NASA) — around 24 cm wavelength. This radar can penetrate through forest canopy, soil, vegetation, and even ice layers. It’s ideal for studying:
- Land deformation (e.g. tectonic/ earthquake-related shifts)
- Ice sheets & glaciers (glacial movement, cryosphere changes)
- Forest biomass and subsurface changes
- S-band SAR (provided by ISRO) — shorter wavelength (around 12 cm). This one is more sensitive to surface-level features, good for:
- Agricultural monitoring (crop health, soil moisture)
- Wetlands, forests, vegetation cover changes
- Snow cover, land-use / land-cover studies, surface deformation.
Some technical highlights:
- The radar system is fully polarimetric and interferometric, enabling 3-D mapping of surface changes.
- The imaging swath is very wide — around 240 km — which allows large-scale observations with each pass.
- Because it is radar-based, NISAR’s imaging is not affected by clouds, daylight, or weather — ensuring consistent, all-weather, day-night data.
Primary Objectives & Scientific Goals of NISAR Mission
NISAR aims to address several critical Earth-science and socio-economic themes:
- Monitor land deformation and geology — track tectonic shifts, earthquake zones, landslides, crustal movements.
- Cryosphere & Ice-sheet Studies — observe glaciers, polar ice sheets, ice-sheet dynamics, contributing to understanding sea-level rise and climate change.
- Ecosystem & Vegetation Monitoring — assess forest cover, biomass, deforestation, land-use / land-cover change, wetlands, wetlands degradation, and other ecological changes.
- Agriculture & Soil Moisture / Land-use Studies — monitor crop conditions, soil moisture, land-use changes, which can aid in agricultural planning and water-resource management.
- Disaster Management & Natural Hazard Monitoring — enable early detection and monitoring of disasters like earthquakes, landslides, floods, ground subsidence; help mitigation.
- Climate Change & Environmental Studies — track ecosystem changes, deforestation, groundwater changes, coastal changes, glacial melt — all critical for understanding climate-change impacts.
In short: NISAR provides a global, regular, high-resolution radar “X-ray” of Earth, offering data for science, policy, management, and planning related to environment, climate, disaster risk, agriculture, water, and more.
Significance — Why NISAR Matters
- All-weather, day/night imaging — unlike optical satellites, NISAR ignores clouds/ darkness; ensures consistent data. This is vital for tropical countries (like India) with frequent cloud cover.
- Dual-frequency radar = deeper & surface insights — combining L- and S-band gives a more holistic picture of Earth: both the surface and the subsurface.
- Global coverage with frequent revisit — entire Earth’s land & ice-covered regions imaged roughly every 12 days; useful for monitoring rapid changes.
- Multidisciplinary applications — environment, climate, geology, disaster management, agriculture, water resources: NISAR’s data will be used across sectors.
- Strategic value for India & world — for a country like India with mountains, glaciers, flood zones, forests, agriculture — NISAR data can inform planning, early warning systems, and resource management.
- Strengthening India-US Space Collaboration — the mission is a significant milestone in bilateral cooperation, combining NASA’s radar-imaging expertise with ISRO’s launch and satellite-bus capabilities.
FAQs
NISAR is a joint NASA-ISRO satellite using dual-band radar to study Earth’s ecosystems, natural hazards and climate-related changes.
The 12-metre reflector enables high-resolution radar mapping essential for monitoring forests, ice sheets, coastline movements and crop patterns.
Its first S-Band radar imagery covers the Godavari River Delta, with calibration scenes captured in India and the Amazon rainforest.
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