The NASA-ISRO Synthetic Aperture Radar (NISAR) mission has achieved a major engineering milestone: the successful deployment of its 39-foot (12-meter) drum-shaped antenna reflector in low Earth orbit. The massive reflector, stowed like an umbrella during launch, unfurled after its 30-foot (9-meter) boom extended and locked in place.
Launched on July 30, 2025, from the Satish Dhawan Space Centre in India, NISAR is a flagship collaboration between NASA and the Indian Space Research Organisation (ISRO). The satellite will track ice sheet motion, land deformation from earthquakes and volcanoes, landslides, and ecosystem changes with unmatched precision — down to fractions of an inch.
Why the Reflector Matters
Weighing about 142 pounds (64 kilograms), the reflector is made of 123 composite struts and a gold-plated wire mesh. It unfurled through a process engineers call the “bloom.” In this process, small explosive bolts released the structure. This release allowed stored tension to expand it into place. Motors and cables then locked it securely.
The reflector acts as the “lens” for NISAR’s dual-band radar system:
- L-band radar (NASA) – penetrates clouds and forest canopies, critical for monitoring glaciers and earthquakes.
- S-band radar (ISRO) – sensitive to vegetation and soil moisture, essential for agriculture and wetland studies.
“The successful deployment of NISAR’s reflector marks a significant milestone,” said Karen St. Germain, director of NASA’s Earth Science Division. “The data NISAR will gather will have a major impact on global disaster response, infrastructure monitoring, and food security.”
The Largest of Its Kind
At 39 feet across, NISAR’s reflector is the largest antenna ever deployed for a NASA mission. Without its synthetic aperture radar (SAR) technology, a conventional radar antenna would need to be 12 miles (19 kilometers) long to achieve the same resolution.
“This is the largest antenna reflector ever deployed for a NASA mission,” said Phil Barela, NISAR project manager at NASA’s Jet Propulsion Laboratory (JPL). “It’s a critical part of the mission and has taken years of design and testing.”
NISAR can capture images using SAR with a 30-foot (10-meter) resolution. With interferometric techniques, it can generate 3D time-lapse “movies” of Earth’s surface changes.
Building on Decades of Radar Innovation
NISAR represents the culmination of more than 40 years of radar heritage at NASA’s JPL. This legacy spans from the Seasat mission in 1978 to Magellan, which mapped Venus in the 1990s.
The mission also reflects deep U.S.-India space cooperation. ISRO contributed the S-band radar and spacecraft bus, while NASA provided the L-band radar, reflector, boom, and data systems. Launch operations were handled in India, with global tracking by ISRO’s Telemetry, Tracking and Command Network.
Looking Ahead
Now fully deployed, NISAR will undergo fine-tuning before beginning its science operations in late fall 2025. Once operational, it will provide unprecedented radar imaging of Earth. This imaging will support research and policy in climate change. It will also aid in disaster preparedness and sustainable development.
As Paul Rosen, NISAR’s project scientist at JPL, explains: Synthetic aperture radar works like the lens of a camera. Without it, spaceborne radars would only provide rough data. With SAR, NISAR will deliver sharp, high-resolution imagery that can reveal how our planet is changing — in real time.