ISRO-NASA ‘NISAR Mission’

By R Anil Kumar

• The latest NASA-ISRO collaboration follows the successful mission to the International Space Station by Astronaut Group Captain Shubhanshu Shukla

• NISAR will help Global Community Monitor Earth Changes- ISRO Chairman V Narayanan

• The highly anticipated NISAR (NASA-ISRO Synthetic Aperture Radar) mission is set to launch on July 30 at 5:40 PM from Sriharikota aboard the GSLV-F16 rocket. Developed through over a decade of collaboration between ISRO and NASA’s Jet Propulsion Laboratory, NISAR is the first Earth observation mission to carry a dual-band radar system (NASA’s L-band and ISRO’s S-band)

• It aims to revolutionize the way we monitor Earth’s land, ice, and natural disasters. The satellite, weighing 2,392 kg, will use SweepSAR technology to capture high-resolution, all-weather data every 12 days. This marks a milestone as the 102nd launch from Indian soil and will significantly benefit global scientific and disaster mitigation efforts

Bengaluru. The unique Earth observation satellite NASA-ISRO Synthetic Aperture Radar (NISAR) will be launched through the GSLV-S16 on July 30, said ISRO chairman V Narayanan.

In a historic collaboration between the United States and India, the NASA-ISRO Synthetic Aperture Radar satellite, also known as NISAR, is poised to revolutionise how we observe and understand our planet.

Scheduled for launch on the evening of July 30 from the Satish Dhawan Space Centre in Andhra Pradesh’s Sriharikota, NISAR represents the largest joint Earth science mission ever undertaken by NASA and the Indian Space Research Organisation (ISRO). The latest NASA-ISRO collaboration follows the successful mission to the International Space Station by Astronaut Group Captain Shubhanshu Shukla.

At its core, NISAR is designed to monitor changes in Earth’s surface with unprecedented precision, capturing movements as small as a centimetre. This capability is vital for tracking natural hazards such as earthquakes, landslides, volcanic activity, and glacial shifts, as well as human-induced changes like urban expansion, agricultural development, and infrastructure stress.

ISRO says the NISAR satellite weighs 2,392 kg, and it will scan the entire globe and provide all-weather, day-and-night data at a 12-day interval and enable a wide range of applications. NISAR can detect changes in the Earth’s surface, such as ground deformation, ice sheet movement and vegetation dynamics.

Further applications include sea and ice classification, ship detection, shoreline monitoring, storm characterisation, changes in soil moisture, mapping and monitoring of surface water resources and disaster response.

What sets NISAR apart is its dual-frequency radar system, a first-of-its-kind configuration in space. NASA has contributed the L-band radar, which penetrates vegetation and soil to reveal subsurface changes, while ISRO has provided the S-band radar, optimised for detecting surface-level features like foliage and terrain. These radars are mounted on a 12-meter mesh reflector antenna, roughly the size of a school bus, allowing the satellite to scan nearly all of Earth’s land and ice surfaces twice every 12 days.

The satellite’s ability to operate day and night, in all weather conditions, ensures a continuous and reliable stream of data. This is especially critical for regions prone to disasters, where timely information can mean the difference between life and death. As Nikki Fox, Associate Administrator for NASA’s Science Mission Directorate, emphasises, “NISAR’s data will help ensure the health and safety of those impacted on Earth, as well as the infrastructure that supports them.”

Beyond disaster response, NISAR will play a pivotal role in climate science, ecosystem monitoring, and resource management. It will help track groundwater depletion, forest density, wetland flooding, and coastal vegetation, offering insights that are essential for food and water security. More than 180 organisations from local governments to private companies are already preparing to use NISAR’s data to inform decisions and policies.

The mission also showcases the power of international cooperation. As Wendy Edelstein, NISAR’s Deputy Project Manager at NASA’s Jet Propulsion Laboratory (JPL), noted, “NISAR is a 50-50 partnership between NASA and ISRO. It represents the largest collaboration in space between the United States and India.” It has cost upwards of $1.3 billion.

The satellite was built and tested over five years, with extensive integration work carried out in both countries. Ms Edelstein herself spent over 150 days in India working alongside ISRO engineers, highlighting the deep commitment and mutual respect between the two space agencies.

Technologically, NISAR employs synthetic aperture radar (SAR) and interferometry to create high-resolution images and detect surface motion. SAR allows the satellite to simulate a much larger antenna by combining thousands of radar pulses, resulting in detailed imagery. Interferometry, on the other hand, enables the measurement of ground displacement over time by comparing radar signals from different passes. These techniques provide a 3D view of Earth’s surface dynamics, crucial for understanding tectonic shifts, glacier movements, and land subsidence.

The satellite’s data will be open and accessible, aligning with NASA’s commitment to open science. This ensures that researchers, policymakers, and emergency responders worldwide can benefit from NISAR’s insights. As Karen St. Germain, Director of NASA’s Earth Science Division, puts it, “NISAR is a model for the next generation of Earth observation capabilities.”

For India, NISAR is a strategic milestone in its growing space ambitions. It complements the country’s Gaganyaan human spaceflight program, recent lunar and solar missions, and its expanding role in global space diplomacy. The launch also underscores India’s technical prowess, with ISRO providing the Geosynchronous Satellite Launch Vehicle (GSLV-F16) launch vehicle, spacecraft bus, solar arrays, and ground support.

The excitement surrounding NISAR is palpable. Paul Rosen, NISAR’s Project Scientist at JPL, described the mission as the culmination of decades of work, calling it a “high-definition movie of the Earth.” He highlighted how NISAR’s radar can “see through foliage, study building footprints, measure flood depth,” and even detect subtle shifts in tectonic plates.

As the countdown to launch begins, NISAR stands as a beacon of scientific innovation and international unity. It promises to deepen our understanding of Earth’s complex systems, enhance our ability to respond to environmental challenges, and inspire future collaborations in space exploration.

NISAR – NASA ISRO Synthetic Aperture Radar Mission

Objective:

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 capability to acquire fully polarimetric and interferometric data.

More Details

The unique dual-band Synthetic Aperture Radar of NISAR employs 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.

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.

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, GPS receiver, 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 manoeuvre plan and 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 the scientists to understand the changes happening to Planet Earth.

Realization of NISAR

The complex payloads and mainframe systems have been designed, developed, qualified and realised over a period of 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 were 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 dia 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 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., manoeuvres, parameter updates, etc.), will be generated pre-launch via frequent coordination between JPL and ISRO.

(Images and Data Source: ISRO-NASA)