NISAR soars: Indo-US ‘golden mesh’ to track Earth’s pulse from orbit

India and the United States have jointly launched the NASA-ISRO Synthetic Aperture Radar (NISAR) satellite, a landmark Earth observation mission that blends technical prowess with international partnership. Lifted off at 17:40 on 30 July 2025 aboard ISRO’s GSLV Mk II rocket from the Satish Dhawan Space Centre in Sriharikota, the 2,380-kilogram satellite was inserted into a 745-kilometre sun-synchronous orbit just over 18 minutes after liftoff.

The mission is the first Earth-observing satellite developed jointly by the Indian Space Research Organisation (ISRO) and the United States’ National Aeronautics and Space Administration (NASA). It represents the first collaboration between the two agencies on satellite hardware, and also the first time a GSLV Mk II has been used to launch a payload into a polar orbit.

Earlier, briefing the media on 27 July, the Union Minister for Science and Technology, Dr Jitendra Singh, called the launch a historic moment for India’s growing scientific footprint. “This mission is not just about a satellite launch—it is a moment that symbolises what two democracies committed to science and global welfare can achieve together,” he said. “NISAR is not just a satellite; it is India’s scientific handshake with the world.”

Built Across Continents, Engineered for Precision

NISAR measures approximately 5.5 metres and houses a dual-radar system never before flown together—NASA’s L-band radar and ISRO’s S-band radar. It also carries two deployable solar arrays, each 5.5 metres long, with a combined surface area of 23 square metres. Together, they generate about 5 kilowatts of power to support the satellite’s operations. The spacecraft includes 15 thrusters to enable precise manoeuvring in orbit.

The NISAR will orbit Earth 14 times a day, scanning regions critical to understanding climate change, disaster risk, and natural resource patterns.

The L-band system, developed by NASA’s Jet Propulsion Laboratory (JPL) in Southern California, uses a 25-centimetre wavelength to penetrate dense vegetation and measure subsurface deformation. ISRO’s S-band radar, built at the Space Applications Centre in Ahmedabad, operates at a 10-centimetre wavelength, better suited for capturing surface-level changes and shorter vegetation like shrubs and bushes.

These two radars will operate in synchronisation, collecting data that is temporally and spatially aligned, thereby extending the measurement sensitivity across a wide range of surface conditions and object sizes. This will allow NISAR to detect elevation changes as small as 1 centimetre over a plot of land about the size of half a tennis court—an unprecedented level of precision for a radar satellite.

Central to this architecture is a deployable boom measuring 9 metres in length, which supports a 12-metre-diameter gold-coated mesh antenna reflector. The reflector, when unfurled, resembles a snare drum and is responsible for transmitting and receiving radar signals across a 242-kilometre swath. NISAR’s imaging coverage will span nearly all of Earth’s land and ice surfaces every 12 days, operating day and night, through clouds, and in all weather conditions.

The spacecraft was integrated using a modified ISRO I3K satellite bus. After JPL and ISRO engineers completed the integration and environmental testing of the system, ISRO transported the satellite from California to the Satish Dhawan Space Centre in May 2025 to prepare for launch.

NASA provided the L-band radar and associated systems, including the antenna reflector, the boom, the high-rate communication subsystem, solid-state recorder, GPS receivers, and payload data systems. ISRO contributed the S-band radar, satellite bus, launch vehicle, and mission operations support.

ISRO is responsible for the launch vehicle, mission operations via the ISRO Telemetry Tracking and Command Network, and data handling through the National Remote Sensing Centre, which will process and distribute the S-band data for Indian stakeholders. The L-band data will be transmitted through NASA’s Near Space Network and stored via cloud systems to handle the mission’s data-intensive nature.

A Platform for Open Science and Global Impact

The satellite builds upon decades of radar innovation. Synthetic Aperture Radar (SAR) was first used by NASA in 1978 aboard Seasat. ISRO followed with its first SAR mission, RISAT-1, in 2012 and later RISAT-1A in 2022. Unlike previous missions, NISAR merges SAR systems from both agencies to deliver higher sensitivity, wider coverage, and faster revisit times.

This configuration will support applications across multiple domains, including sea ice tracking, ship detection, storm monitoring, soil moisture mapping, agricultural planning, and disaster response. NISAR will also offer unparalleled views of Antarctica, where the satellite’s radar will monitor ice sheet deformation and freshwater runoff into oceans.

NASA Deputy Associate Administrator Casey Swails said the mission exemplifies the depth of collaboration possible between nations. “This Earth science mission is one of a kind, and really shows the world what our two nations can do,” she said. “It is a pathfinder for building technical and cultural bridges across continents.”

ISRO Chairman Dr V Narayanan praised the precision and success of the mission, calling it an outstanding demonstration of teamwork. “Let me congratulate all the teams from ISRO and NASA JPL on this success,” he said following confirmation of payload separation.

Lt Gen AK Bhatt (Retd.), Director General of the Indian Space Association (ISpA), said the success of NISAR would open doors for India’s private space ecosystem. “This mission paves the way for dynamic Indian private space sector participation in future global collaborations. NISAR’s advanced radar capabilities will generate vital data to address climate change, disaster response, and resource management,” he said.

During its three-year prime mission, NISAR is expected to generate approximately 100 petabytes of science data—roughly 80 terabytes per day, enough to fill around 150 commercial hard drives daily. The data will be processed and distributed via the cloud and made freely available to the public, aligning with NASA’s open-science principles. All Indian government users will also have access to both L-band and S-band data via ISRO’s National Remote Sensing Centre.

With a joint investment of more than USD 1.5 billion—80% funded by NASA—NISAR stands as a technological, scientific, and diplomatic milestone. As Minister Singh noted, “This is the start of a new era in international space collaboration, one where India is not just participating but helping to shape the global commons.”