What will Nisar be looking at in space? In simple terms: nearly everything that matters for Earth’s survival, from the slow grind of tectonic plates to the vanishing breath of forests, from swelling seas to invisible carbon shifts in the atmosphere.
The Nasa-Isro Synthetic Aperture Radar (Nisar) satellite is a first-of-its-kind Earth observation mission that’s ready to monitor climate change, carbon emissions, and natural disaster patterns with unprecedented precision.
The $1.3 billion satellite was launched by Isro from the Satish Dhawan Space Centre in Sriharikota on Thursday.
In an exclusive interview, Paul Rosen, Project Scientist at Nasa, explained why Nisar is different — both in design and purpose — from anything humanity has launched before.
“Nisar carries two powerful radars,” Rosen says, “one built by Nasa and the other by Isro. This dual radar system allows us to scan vast swaths of the Earth every 12 days and build almost cinematic, three-dimensional time-lapse maps of changes happening to glaciers, forests, and coastlines.”
What enables this high-resolution monitoring is Synthetic Aperture Radar (SAR) — a technology Rosen calls “almost magical.”
Instead of relying on visible light like a regular camera, SAR sends microwave pulses toward Earth and collects echoes. While each pulse has low resolution on its own, the satellite processes thousands of such echoes to synthetically create the effect of a massive antenna — giving it the ability to “see” Earth’s surface in detail as fine as 5 to 10 meters.
And this radar doesn’t blink. “Unlike optical satellites,” Rosen explains, “SAR works in all weather, day or night. It’s ideal for imaging forest fires, floods, or earthquakes — even when clouds or smoke obscure the ground.”
The mission also has sharp scientific priorities: monitoring ice sheets, sea ice, agricultural patterns, wetland flooding, and especially above-ground carbon variability. According to Rosen, “One of our key goals is to help carbon modellers better understand how much carbon is stored and released by forests and crops. That’s crucial for fighting climate change.”
Another groundbreaking application is in tracking tectonic plate movements. Using a technique called radar interferometry, Nisar can detect ground shifts as small as a few millimeters, allowing scientists to monitor stress accumulation along fault lines. “We’ll be able to map the Earth’s motion before and after earthquakes and improve models for future risk,” Rosen said.
The hardware behind this mission is just as ambitious. A massive, unfolding radar reflector mounted on a boom enables the wide-angle scans, and the satellite combines S-band (built by Isro) and L-band (from Nasa) radar frequencies — a world-first for free-flying space missions.
The collaboration between Nasa and Isro, Rosen says, has been one of the mission’s highlights. “Isro brings unmatched experience in turning data into real-world applications. We learned a lot from them, and they from us. It’s been deeply rewarding.”
With subsystems already being activated, Nisar is expected to become fully operational within weeks. Once live, it will provide scientists and governments with real-time insights into Earth’s evolving systems — from the fragile crust beneath us to the living carbon engines above.
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