Meet NISAR – the NASA-ISRO Synthetic Aperture Radar mission.

The NASA-ISRO Synthetic Aperture Radar mission, known as NISAR, represents a groundbreaking collaboration between two space agencies, NASA (United States) and ISRO (India).

The mission's goal is to deploy a dual-frequency synthetic aperture radar (SAR) satellite to observe and measure Earth's surface changes with unprecedented detail and frequency.

On July 30, 2025 (17:40 IST), India’s GSLV-F16 rocket lifted off from the Satish Dhawan Space Centre carrying NISAR—the NASA–ISRO Synthetic Aperture Radar satellite—into a sun-synchronous, ~747 km orbit. The mission, a first-of-its-kind U.S.–India collaboration, is designed to tackle some of the most complex and urgent environmental and geological challenges facing our planet.

What Is NISAR?

NISAR is a next-generation Earth observation satellite that uses two radar frequencies—L-band and S-band—to capture high-resolution images of the Earth's surface, regardless of weather conditions or sunlight. This capability allows it to "see" through clouds, rain, and even dense vegetation, providing comprehensive data on land, ice, and ocean surfaces.

Unlike traditional optical imaging satellites, radar can operate day and night, making continuous monitoring possible. NISAR's dual-frequency radar is the first of its kind in space, enabling scientists to obtain a richer, more detailed view of Earth’s dynamic surface processes.

Earth is always moving—tectonic plates shift, volcanoes breathe, cities sink millimeter by millimeter as groundwater is pumped, forests grow and are cleared, glaciers flow. NISAR is designed to measure these subtle motions and map land, ice, and vegetation with a regular, repeatable cadence so scientists, planners, and disaster managers can see change as it happens—and respond. Over a baseline mission of three years for NASA and five years for ISRO, NISAR will generate a consistent, openly available record of Earth’s dynamics.

What makes NISAR unique

Dual-Frequency Synthetic Aperture Radar (SAR)

L-band SAR: Operates at a 24 cm wavelength, allowing deeper penetration into vegetation and the Earth's surface to study landscape topography and dense forests.

S-band SAR: Uses a 10 cm wavelength providing high-resolution imagery suited for soil moisture monitoring and polar region observations.

Each radar operates with a wide swath width of 242 km, enabling the satellite to survey large areas quickly and repeatedly.

SweepSAR Technique

NISAR employs an advanced SweepSAR technology. Instead of scanning narrow strips sequentially, SweepSAR transmits radar signals over a large swath all at once and receives echoes rapidly from different parts. This enables the satellite to combine data for high-resolution images over vast regions with high temporal frequency.

Instrument and Spacecraft Features

• A 12-meter (39 feet) deployable mesh antenna, the largest reflector antenna launched by NASA, folds compactly for launch and deploys in orbit.

• Three-axis stabilization ensures precise instrument pointing and data accuracy.

• The satellite orbits Earth at approximately 747 km altitude with a 98.4° inclination, enabling global coverage every 12 days.

• It carries a solid-state recorder, GPS receivers, and a high-rate telecommunication subsystem for fast data transmission.

Mission Objectives and Scientific Goals

1. Solid Earth & Hazards

   • Track earthquake fault creep, volcanic inflation, and landslides by measuring ground motion with centimeter- to millimeter-level sensitivity using repeat-pass interferometry.

   • Map subsidence in cities and agricultural basins due to groundwater withdrawal—vital for infrastructure safety and water policy.

2. Cryosphere

   • Monitor Greenland and Antarctic ice sheets, mountain glaciers, and sea ice to improve projections of sea-level rise and freshwater availability.

3. Ecosystems & Biomass

   • Estimate woody biomass and its change (carbon accounting), track crop extent and health, and map wetlands dynamics—key for climate mitigation and food security.

4. Disaster response

   • Provide rapid mapping for floods, earthquakes, and volcanic eruptions, guiding relief and recovery with consistent, cloud-penetrating radar imaging—day or night.

How the mission is built and flown

• Workshare:

  • NASA: L-band SAR; 12 m reflector and 9 m boom; high-rate Ka-band telecom; GPS; solid-state recorder; instrument structure and engineering payload.

  • ISRO: S-band SAR; spacecraft bus (I-3K class); GSLV Mk-II launcher; operations.

• Launch & orbit details:

  • Launched July 30, 2025 on GSLV-F16 into ~743–747 km, 98.4° sun-synchronous orbit; a 90-day commissioning phase follows for deployments and calibration.

How NISAR Data Will Be Used

NISAR will be a data powerhouse—designed for wide swaths and frequent revisits—with daily volumes high enough to demand robust ground systems. Data will be free and open, hosted by the Alaska Satellite Facility (ASF) DAAC for NASA streams, with NRSC/Bhoonidhi distribution for Indian users (including S-band products). Expect routine, analysis-ready products to support both research and decision-making.

What this means for India (and the world)

For India, NISAR’s S-band brings sharper sensitivity to agriculture, wetlands, coasts, and soil moisture, while L-band strengthens measurements of biomass and land/ice deformation. Together they bolster food security planning, groundwater and subsidence monitoring, coastal management, infrastructure risk assessment, and disaster preparedness—with global benefits from an open data policy and harmonized NASA–ISRO operations.

The bottom line

NISAR is the most capable civilian radar mapper ever put in orbit: dual-band eyes, a stadium-sized antenna, clever SweepSAR scanning, and a commitment to open data. It’s a flagship for Earth science and international partnership—built to turn subtle surface shifts into actionable knowledge for climate, hazards, and sustainability.

Sources: Launch confirmation and details from ISRO and NASA; technical characteristics and operations from NASA’s NISAR mission pages; additional launch specifics from NASASpaceflight’s report on the GSLV-F16 mission.