08-19-2025

NISAR satellite unfurls antenna in orbit, set to begin unprecedented Earth imaging mission

ByRodielon Putol

Earth.com staff writer

The NISAR mission – short for NASA-ISRO Synthetic Aperture Radar – has successfully deployed its massive 39-foot antenna reflector in space.

Seventeen days after launch, the reflector, which had been folded up like an umbrella, finally unfurled after the satellite’s 30-foot boom was fully extended and locked in place. Now it’s ready to begin its work monitoring Earth in stunning detail.

The mission is a collaboration between NASA and the Indian Space Research Organisation (ISRO). It launched on July 30 from the Satish Dhawan Space Centre in southeastern India.

From its orbit, NISAR will track movements in ice sheets, glaciers, and land surfaces affected by earthquakes, volcanoes, and landslides. It will also monitor forests and wetlands with precision down to a fraction of an inch.

“The successful deployment of NISAR’s reflector marks a significant milestone in the capabilities of the satellite,” said Karen St. Germain, director of NASA’s Earth Science Division.

“From innovative technology to research and modeling to delivering science to help inform decisions, the data NISAR is poised to gather will have a major impact on how global communities and stakeholders improve infrastructure, prepare for and recover from natural disasters, and maintain food security.”

Why this antenna matters

This reflector is the largest ever deployed for a NASA Earth science mission.

It’s built to handle two powerful radar systems at once: an L-band radar that can see through clouds and trees, and an S-band radar that’s better at detecting changes in light vegetation and wet snow. The reflector is essential to both.

“This is the largest antenna reflector ever deployed for a NASA mission, and we were of course eager to see the deployment go well. It’s a critical part of the NISAR Earth science mission and has taken years to design, develop, and test to be ready for this big day,” said Phil Barela, NISAR project manager at NASA’s Jet Propulsion Laboratory (JPL).

“Now that we’ve launched, we are focusing on fine-tuning it to begin delivering transformative science by late fall of this year.”

How the antenna opened in orbit

The reflector weighs around 142 pounds and is built from 123 composite struts and a gold-plated wire mesh.

On August 9, the satellite’s boom began unfolding, one joint at a time. Four days later, it was fully extended. The reflector assembly, attached to the end of the boom, was next.

On August 15, small explosive bolts fired to release the reflector. This kicked off the “bloom” – a gradual unfurling that relied on tension built up in the frame while it was stowed. Motors and cables then pulled it into its final locked position.

To image Earth’s changing landscape at about 30-foot resolution, the antenna had to be big – about the width of a school bus. Without synthetic aperture radar (SAR), the same level of detail would require a traditional antenna nearly 12 miles long.

A new lens on Earth’s surface

“Synthetic aperture radar, in principle, works like the lens of a camera, which focuses light to make a sharp image. The size of the lens, called the aperture, determines the sharpness of the image,” explained Paul Rosen, NISAR’s project scientist at JPL.

“Without SAR, spaceborne radars could generate data, but the resolution would be too rough to be useful. With SAR, NISAR will be able to generate high-resolution imagery.”

Using special interferometric techniques that compare images over time, NISAR enables researchers and data users to create 3D movies of changes happening on Earth’s surface.

NISAR builds on decades of radar research. It follows earlier missions from JPL, including Seasat in 1978 and Magellan in the 1990s, which mapped the surface of Venus. But this is the first time two SAR systems have flown together on a single Earth science satellite.

The technology has come a long way, and the stakes are real.

NISAR isn’t just about pretty pictures from space. It’s about tracking the changes happening on our planet – shifting ice, sinking coastlines, moving fault lines – so we can respond faster, plan smarter, and understand the systems we all depend on to live, grow food, and stay safe.