Using L-band radar data from the U.S.-India NISAR (NASA-ISRO Synthetic Aperture Radar) satellite, scientists have captured a striking image of Nunatak Zaterjavshijsja. This East Antarctic mountaintop emerges from a rapidly moving stream of ice flowing toward the ocean. The presence of the mountain creates significant structural stress, resulting in deep fractures known as crevasses, which appear as sharp green lines in the radar imagery. Created in August 2025, the distinctive formation has earned the nickname “the hummingbird” among the NISAR scientific team.
The visualization utilizes color coding to represent how polarized microwave signals interact with the Antarctic surface. As the NISAR satellite transmits radar waves toward Earth with horizontal polarization, the orientation of the returning signals—whether horizontal, vertical, or a combination of both—reveals critical details about the terrain.
Signals returning with horizontal polarization typically indicate reflections from smoother surfaces, such as uniform ice, which are rendered in magenta. Conversely, signals returning with vertical polarization indicate volume scattering, occurring when waves penetrate the ice or scatter off irregular surfaces like crevasse walls; these are displayed in green. Areas where both horizontal and vertical signals reflect strongly are shown in white, indicating a balanced blend of surface and volume scattering.
Figure A is an annotated version of image.
The NISAR project is a collaborative effort: NASA’s Jet Propulsion Laboratory, managed by Caltech, oversees the United States component and provided the L-band SAR and antenna reflector. The Indian Space Research Organisation provided the spacecraft bus and the S-band SAR. As the first satellite to deploy two SAR instruments at different wavelengths, NISAR utilizes a massive 39-foot (12-meter) drum-shaped reflector, marking the largest radar antenna reflector ever launched by NASA.
