NISAR’s L-band radar maps Antarctica’s “hummingbird” and exposes stressed ice cracks

NASA’s NISAR satellite has produced an Antarctica image that scientists have nicknamed “the hummingbird.” The “hummingbird” is Nunatak Zaterjavshijsja, a mountaintop in East Antarctica that pokes out amid a stream of ice flowing northeast to the ocean, and the radar view captures exactly how that obstruction changes the ice around it.

In the image, produced in August 2025, NISAR’s L-band radar shows deep cracks and fractures, called crevasses, appearing as sharp green lines. That matters because it turns a dramatic, almost poetic label into something operational for anyone who has to monitor ice stability: the satellite is not just seeing terrain, it is mapping stress patterns implied by how the ice surface and interior scatter polarized microwave signals.

So what is NISAR actually doing here? Over Antarctica, the satellite transmits radar waves with a horizontal polarization. When the returned signals come back horizontally polarized, they likely bounced off a more regular surface, such as smoother ice, and those signals appear magenta in the image. Signals that return with vertical polarization may have refracted as they partially penetrated the ice or scattered at different angles as they reflected from irregular surfaces, like crevasse faces. In the visualization, those “volume scattering” observations are displayed in green. The white areas represent places where both magenta and green signals scatter back strongly, a possible indication that there is an equal blend of surface and volume scattering.

The vivid color scheme is doing serious work. Polarized radar is effectively a detector of differences in how the ice interacts with microwave energy, including both the top surface and deeper or internal scattering. In plain terms: smooth ice tends to give one kind of return, while cracked or rough features give another. When a mountaintop juts into a moving ice stream, it can force stresses into the flow. NISAR’s image ties that physical setup to what the radar detects: the obstruction sits amid northeast-flowing ice, and the surrounding areas show heavily fracturing surfaces with deep crevasses.

This is also a platform story, not just a picture. NISAR is the first satellite to carry two synthetic aperture radar instruments at different wavelengths, collecting data using a giant drum-shaped reflector that measures 39 feet (12 meters) wide, the largest radar antenna reflector NASA has ever sent into space. In the program architecture, NASA’s Jet Propulsion Laboratory leads the United States component of the project and provided the satellite’s L-band SAR and antenna reflector. The spacecraft bus and its S-band SAR were provided by the Indian Space Research Organisation. That division of labor matters because it underscores why executives who fund, govern, or partner on space systems care about NISAR: it is a complex, cross-agency, dual-wavelength radar platform built to produce repeatable Earth observations, not a one-off experiment.

Now zoom out to why decision-makers should pay attention to a “hummingbird” in Antarctica. First, radar that can distinguish surface scattering from volume scattering is a powerful monitoring tool in environments where optical imaging struggles. Antarctica is bright, windy, and often cloud-covered, which makes consistent visual observation difficult. Radar, particularly polarized radar, can keep producing signals as conditions change. Second, ice features like crevasses are not just geology trivia. They are mechanical stress evidence, and mapping them at scale is part of understanding how ice responds to forces and flows.

Third, this kind of capability feeds the policy and risk side of the world. Even without turning this single image into a headline-grabbing prediction, it strengthens the evidence base for climate and Earth-system monitoring. For boards and investors, that matters in the broader way: the value chain is moving toward high-frequency, high-resolution sensing that can be used in scientific analysis and, eventually, in the models and decisions that follow. NISAR’s approach is a reminder that “data products” from space can be designed for interpretation, not just detection.

Bottom line: NISAR’s L-band radar didn’t just spot a mountaintop called Nunatak Zaterjavshijsja. It mapped the surrounding ice’s response to that obstruction by showing deep crevasses as sharp green lines, derived from how horizontal and vertical polarization returns behave. If you are an executive tracking space-enabled analytics, climate monitoring, or cross-border science infrastructure, this is the kind of real, technical measurement that turns remote sensing from pretty visuals into usable insight.