Nasa-Isro Synthetic Aperture Radar (NISAR)

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Nasa-Isro Synthetic Aperture Radar (NISAR)

Nasa-Isro Synthetic Aperture Radar

The Brief by InclusiveIAS

Table of Contents

Key Facts

Launch Date: 30 July 2025
Mission Partners: ISRO and NASA
Launch Vehicle: GSLV Mk-II, from Satish Dhawan Space Centre, Sriharikota
Nature: Earth Observation Satellite (Dual-Frequency SAR)
Orbit & Operation: After launch, NISAR will enter a sun-synchronous polar orbit (747 km altitude, 98.4° inclination) and use Synthetic Aperture Radar (SAR) to bounce radar waves off Earth’s surface, measuring return time and phase changes instead of capturing optical images.
Mapping Cycle: Covers almost entire Earth every 12 days; completes 14 orbits/day
- In just 97 minutes, Nisar will circle the planet once
Mission Life: 5 Years(ISRO)
Contribution:
- NASA: L-band radar, electronics, GPS, engineering support
- ISRO: S-band radar, satellite bus, launch, ground systems
Science & Application Scope: NISAR’s mission covers six major domains – solid Earth processes, ecosystems, ice dynamics, coastal and ocean processes, disaster response, and additional applications such as tracking groundwater, oil reservoirs, and infrastructure (levees, dams, roads) for subsidence or deformation, as well as supporting food security research.

Objectives

NISAR mission’s primary objectives are to study land & ice deformation, land ecosystems, and oceanic regions in areas of common interest to the US and Indian science communities.

NISAR mission will help to

measure the woody biomass and its changes
track changes in the extent of active crops
understand the changes in wetlands’ extent
map Greenland’s & Antarctica’s ice sheets, dynamics of sea ice and mountain glaciers
characterize land surface deformation related to seismicity, volcanism, landslides, and subsidence & uplift associated with changes in subsurface aquifers, hydrocarbon reservoirs, etc.

Key Technology

Dual-Frequency SAR (first in the world): NISAR is the first satellite to use two different radar frequencies – L-band (24 cm wavelength, built by NASA) and S-band (12 cm wavelength, developed by ISRO) – for Earth observation, enabling comprehensive surface monitoring.
- Most radar imaging satellites work with a single frequency, but NISAR’s dual system allows it to “see” through clouds, thick forest canopies, smoke, and even in complete darkness.
  - Both frequencies penetrate clouds and forest canopies, although the lower L-band frequencies can penetrate thicker vegetation so the Earth’s surface can be monitored independently of coverage. As such the L-SAR will be used to observe landscape topography and heavily forested areas. The higher S-band frequencies will be used to monitor soil moisture, particularly in polar regions as S-band frequencies are less perturbed by the ionosphere.
All-Weather, Day-Night Capability: Works through clouds, vegetation, smoke, and darkness
Precision: NISAR can detect changes in the Earth’s surface as small as a few millimeters. This high level of
precision is achieved through its Interferometric Synthetic Aperture Radar (InSAR) technique
Technique: Interferometric SAR (InSAR) – compares radar images over time to detect micro changes.
- This involves taking two radar “photos” (images) of the same location a few days apart and comparing them to detect micro changes in the surface. Even shifts as small as a few millimeters, such as glacier movement, ground subsidence, or post-earthquake displacement, can be identified.
Antenna: 12 m gold-plated deployable mesh – largest radar imaging antenna ever launched into space

Applications

Tracking climate change: Observing polar ice loss, glacier shifts, and permafrost thawing with unprecedented accuracy.
- Map Greenland & Antarctica’s ice sheets, sea ice dynamics, and mountain glaciers
- Track calving rates in polar ice shelves to refine IPCC climate models
Disaster management: Identifying subtle signs of land subsidence, landslide risks, and fault-line movements to predict earthquakes early.
- Map mangrove extent for coastal protection
- It can generate detailed images that aid in predicting potential disasters, guiding post-disaster rescue operations, and developing improved models for earthquakes and volcanic eruptions.
- Its data could help support the Sendai Framework on reducing disaster risk and refine IPCC models.
Agriculture & water security: Forecasting crop yields, monitoring soil moisture, and mapping groundwater depletion to ensure resource sustainability.
Forests & ecosystems: Measuring deforestation, forest biomass, and the carbon storage potential of vegetation to support conservation efforts.

Aquatic organisms are indispensable for ecological balance, human well-being, and planetary health. Protecting them requires integrated efforts involving pollution control, sustainable resource use, and global cooperation to address climate change and biodiversity loss.

UPSC Spot-Check

Prelims

Consider the following statements regarding the NISAR mission:

Statement I: NISAR can detect changes in the Earth’s surface as small as a few millimeters.

Statement II: This precision is achieved using the Interferometric Synthetic Aperture Radar (InSAR) technique,

which compares radar images of the same location taken days apart to identify minute shifts.

Which one of the following is correct?

(a) Both Statement I and Statement II are correct, and Statement II is the correct explanation of Statement

(b) Both Statement I and Statement II are correct, but Statement II is not the correct explanation of Statement

(d) Statement I is incorrect, but Statement II is correct

Mains

Q. The NISAR mission represents a significant advancement in Earth observation technology through its innovative radar systems. Discuss the key technological features of NISAR and analyse its potential

applications.(15 Marks, 250 Words)

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