Explained: GSLV-F16 NISAR

Inspiration Study Circle Explained: GSLV- F16 Nisar

The NISAR (NASA-ISRO Synthetic Aperture Radar) mission is a joint project between the space agencies of the United States (NASA) and India (ISRO). The mission uses advanced radar technology to measure Earth’s changing surfaces, ecosystems, ice masses, and more, according to ISRO.

Launch and spacecraft

NISAR was launched on July 30, 2025, from the Satish Dhawan Space Centre in Sriharikota, India.
It was carried into orbit by an Indian Geosynchronous Satellite Launch Vehicle (GSLV) rocket, specifically the GSLV-F16 variant.
The satellite operates in a sun-synchronous orbit at an altitude of approximately 747 kilometers.
It is designed to map the Earth’s surface and ice-covered regions every 12 days.

Spacecraft Configuration

The Spacecraft is built around ISRO’s I-3K Structure. It carries two major Payloads viz., L & S-Band Synthetic Aperture Radar (SAR). The S-band Radar system, data handling & high-speed downlink system, the spacecraft, and the launch system are developed by ISRO. The L-band Radar system, high speed downlink system, the Solid-State Recorder, the GPS receiver, and the 9m Boom hoisting the 12m reflector are delivered by NASA. Further, ISRO takes care of the satellite commanding and operations, NASA will provide the orbit maneuver plan, and the RADAR operations plan. NISAR mission will be aided with ground station support of both ISRO and NASA for downloading of the acquired images, which, after the necessary processing, will be disseminated to the user community
The data acquired through S-band and L-band SAR from a single platform will help scientists to understand the changes happening to Planet Earth.

The Major Mission Configuration and Joint Work Share responsibilities are detailed below:

Major Mission Characteristics (Joint Mission of ISRO & NASA)
Mainframe Bus	I3K Structure with ~2400Kg Lift Off Mass 70V Bus 3-axis stabilized spacecraft
Imaging Payload	· Dual Frequency (L & S-Band) Synthetic Aperture Radar (SAR). · L-band SAR (NASA); S-band SAR (SAC-ISRO) · Large size 12m diameter common unfurlable reflector antenna mounted on deployable 9m Boom. · ~240 km observable swath with 5-100 m resolution Free and open data policy
Orbit	Sun synchronous, Polar (6 PM)
Orbit altitude	747 km – Circular
Inclination	98.405 deg
Launcher	GSLV Mk-II with 4m PLF
Mission Life	5 Years

Dual-frequency radar

NISAR is the first satellite to utilize dual-frequency radar systems (L-band and S-band) on a single platform.
NASA contributed the L-band radar, which can penetrate through vegetation and ice to study biomass and ice sheet dynamics.
ISRO contributed the S-band radar, which is better suited for monitoring surface-level details like crop health and soil moisture.
These combined capabilities allow NISAR to observe the Earth’s surface in all weather conditions, day and night.

Mission objectives and benefits

NISAR is the first of its kind mission, jointly developed by ISRO and NASA. It is an L and S-band, global, microwave imaging mission, with the capability to acquire fully polarimetric and interferometric data.

The unique dual-band Synthetic Aperture Radar of NISAR employs an advanced, novel SweepSAR technique, which provides high-resolution and large-swath imagery. NISAR will image the global land and ice-covered surfaces, including islands, sea ice, and selected oceans, every 12 days.

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.

The NISAR mission will help to:

Measure the woody biomass and its changes.
Track changes in the extent of active crops.
Understand the changes in the 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.

NISAR’s primary goal is to provide data on land deformation, ice mass dynamics, vegetation biomass, sea-level rise, groundwater changes, and natural hazards such as earthquakes, tsunamis, volcanoes, and landslides.
The mission will generate a vast amount of high-resolution data, providing critical insights for scientists, disaster management authorities, policymakers, and environmental researchers worldwide.
NISAR data will be freely available to the public, fostering global scientific collaboration and benefiting developing countries that may lack similar capabilities.

In essence, the NISAR mission, carried aloft by the GSLV-F16, marks a significant leap forward in Earth observation and international space cooperation, providing unprecedented insights into our planet’s dynamic processes and helping address critical global challenges related to climate change, natural hazards, and resource management.

Realization of NISAR

The complex payloads and mainframe systems have been designed, developed, qualified, and realised over 8 to 10 years.

The S-Band SAR and L-Band SAR were independently developed, integrated, and tested at ISRO and JPL/NASA, respectively.

The Integrated Radar Instrument Structure (IRIS), consisting of S–Band and L–Band SAR and other payload elements, was integrated and tested at JPL/NASA and delivered to ISRO.

Mainframe satellite elements and payloads were assembled, integrated, and tested at URSC/ISRO.

NISAR Mission Phases

NISAR mission phases can be broadly classified into: Launch phase, Deployment Phase, Commissioning Phase, and Science Phase.

Launch Phase:

NISAR will be launched onboard GSLV-F16 launch vehicle on July 30, 2025, from ISRO’s Satish Dhawan Space Centre (SDSC), also referred to as Sriharikota High Altitude Range (SHAR), located in Sriharikota on the southeast coast of the Indian peninsula

Deployment Phase:

NISAR hosts a 12m diameter large reflector, which shall be deployed in orbit 9m away from the satellite by a complex multistage deployable boom designed and developed by JPL/NASA.

Commissioning phase:

The first 90 days after launch will be dedicated to commissioning, or In-Orbit Checkout (IOC), the objective of which is to prepare the observatory for science operations. Commissioning is divided into sub-phases of initial checks and calibrations of mainframe elements, followed by JPL engineering payload and instrument checkout.

Science Operations Phase:

The science operations phase begins at the end of commissioning and extends till the end of mission life. During this phase, the science orbit will be maintained via regular maneuvers, scheduled to avoid or minimize conﬂicts with science observations. Extensive calibration and validation (CalVal) activities will take place. The observation plan for both L and S-band instruments, along with engineering activities (e.g., maneuvers, parameter updates, etc.), will be generated pre-launch via frequent coordination between JPL and ISRO

Significance of GSLV-F16 NISAR for India

NISAR marks a striking shift in how we approach critical sectors such as aviation safety, maritime navigation, coastal management, and urban infrastructure planning.

Launched aboard GSLV-F16, this was the first time ISRO’s GSLV vehicle successfully placed a satellite into a Sun-synchronous Polar Orbit. This 18th flight of the GSLV—and the 12th using the indigenous cryogenic stage—demonstrates India’s growing technological maturity in space systems.

Jointly developed by NASA and ISRO, the NASA-ISRO Synthetic Aperture Radar (NISAR) is the world’s first Earth observation satellite to carry dual-frequency synthetic aperture radars—L-band by NASA and S-band by ISRO—on a single platform. It will deliver high-resolution, all-weather, day-and-night imagery of Earth’s land and ice surfaces, revisiting each location every 12 days.

While NISAR’s applications in disaster management, climate monitoring, glacier tracking, and agriculture are well documented, the satellite’s impact will extend far beyond.

The 2,393-kg satellite was inserted into a 747-kilometre Sun-synchronous orbit. Over its five-year mission life, NISAR will offer invaluable data for global climate science, seismic and volcanic monitoring, forest mapping, and resource management.

The open-access policy for NISAR’s data will empower not only scientists and researchers but also developing countries, disaster-response agencies, and climate change stakeholders worldwide.

Under the visionary leadership of Prime Minister Narendra Modi, India’s space programme is evolving from utility-based missions to knowledge-based initiatives. From Chandrayaan to NISAR, we are not only launching satellites—we are launching new possibilities for global science, sustainability, and shared progress.

Disclaimer: The above information and statistics are sourced from the official website of ISRO and Press Bureau Information on NISAR.

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