NISAR Satellite: Earth's Watchtower Jointly Built By India, US

India and the US' $1.3 billion satellite to decode Earth's secrets is ready for its lift-off from India's space port on the coast of the Bay of Bengal. Made in California's Pasadena and Bengaluru, the NISAR satellite is set to save lives across the world.

The NASA-ISRO Synthetic Aperture Radar (NISAR) satellite, also referred to as the 'Nisarga satellite', is the world's single most expensive civilian Earth imaging satellite. It is being readied to fly aboard India's Geosynchronous Satellite Launch Vehicle (GSLV Mark 2) rocket from Sriharikota on Wednesday. This is the first big Indo-US collaborative satellite mission.

The very unique Earth imaging satellite jointly made by India and the US is a technological marvel and would be game game-changer in saving lives from impending natural disasters. That the world's oldest democracy, the US, and the world's largest democracy, India, are working together on this most expensive satellite is a testament to the growing Indo-US bonhomie and strategic ties.

In an exclusive conversation with NDTV, Dr. Paul Rosen, a NASA Project Scientist for NISAR at the Jet Propulsion Laboratory in California, shared the mission's scientific ambition and its life-saving potential. "This is a science mission and applications mission. We're studying the cryosphere, ecosystems, and solid earth hazards like earthquakes and landslides. It's very much a climate mission," Dr Rosen said.

The satellite's dual-band radar - L-band from NASA and S-band from ISRO - will allow scientists to monitor Earth's surface with unprecedented millimetre precision. This includes tectonic shifts, glacial movements, biomass changes, and even precursors to landslides and glacial lake outbursts.

"We can make 3D movies of the motions of the Earth, all the land and ice. Nothing in conventional remote sensing can do that," Dr Rosen explained.

The use of synthetic aperture radar (SAR) in two bands is a deliberate choice to extend the dynamic range of measurements.

The L-band penetrates deeper and captures larger structures, while the S-band is sensitive to finer details.

"Two wavelengths give us a much more dynamic measurement than just one," he said.

The satellite has been in development for over a decade. On the choice of launch vehicle, Dr Rosen addressed concerns about using the GSLV Mark 2, once nicknamed ISRO's "naughty boy".

"Any launch is risky. But the last GSLV Mark 2 launch was 100% successful in the same configuration we plan to use. I don't have major concerns," he said.

Switching to the newer Launch Vehicle Mark-3 (LVM-30) was considered but ruled out due to cost and time constraints. "Changing midstream incurs costs and delays. It's best programmatically and practically to move forward with GSLV Mark 2," Dr Rosen added.

The NISAR mission was born from NASA's long-standing desire to launch a radar-based Earth observation system. After failed attempts to secure funding, NASA sought international partners. In 2011, Dr Rosen visited India and found enthusiastic support from ISRO.

"I gave a talk about our concept, and it was instantly embraced by ISRO. In 2014, NASA and ISRO signed the agreement. The rest is history," he recalled.

The satellite will provide global coverage every 12 days, enabling continuous monitoring of seismic zones like the Himalayas. "We can measure ground motion to millimetre precision. That helps us understand the earthquake cycle - before, during, and after seismic events," Dr Rosen said.

He also emphasised the satellite's role in tracking landslides and glacial lake outburst floods (GLOFs), which have become increasingly common in the Himalayas. "We can see precursory motion before landslides. And we will monitor glacier dynamics to assess GLOF risks," he noted.

On climate change, NISAR will help quantify carbon exchange between forests and the atmosphere, improving climate models.

"We'll reduce errors in climate modelling by an order of magnitude. That's huge," Dr Rosen said.

Additionally, all data from NISAR will be publicly available.

"The data will be placed in the public archive almost instantly after processing. NASA and ISRO have agreed - this is a science mission, and all radar data will be open," he said.

The collaboration has been technically and culturally enriching. Despite different development styles, both agencies have worked in parallel, integrating components across continents. "ISRO's technology is quite advanced. We built part of the structure, shipped it to India, they added electronics, shipped it back, and it all worked. It's been a great partnership," Dr Rosen said.

On cost disparities, he acknowledged the complexity but emphasised value.

"It's a complex system. But if you divide the cost by the square kilometres of data, it's just 2 US Cents per square kilometer. That's incredibly cheap," he said.

The satellite features a 12-meter unfurlable gold mesh antenna, the largest of its kind in low-Earth orbit. Its boom structure, made of composite fibres, was a new engineering challenge. "It was a challenge to build, but we're confident it will work. We had an extremely complete testing program," Dr Rosen said.

Reflecting on the collaboration, he praised ISRO's engineers and scientists.

"I've been to India over 30 times. The scientists are welcoming, and the engineers are capable. The result is a beautiful satellite that's performing well in tests," he said.

As the launch nears, Dr Rosen is filled with anticipation.

"I've been waiting for this mission for 30 years, working on it for 14. I cannot wait for the data," he said.

And yes, he may be celebrating the launch with peanuts, a JPL tradition, alongside ISRO's temple visits. "Absolutely. I'll celebrate with peanuts and whatever ISRO's tradition is," he laughed.

From Pasadena to Sriharikota, NISAR is more than a satellite - it's a symbol of scientific unity, technological excellence, and a shared commitment to saving lives and understanding our planet.