A mountaintop poking through a river of ice in East Antarctica has produced one of the most striking images yet from the NISAR satellite, a joint mission between NASA and the Indian Space Research Organisation. Scientists have nicknamed the radar capture "the hummingbird."
What the Image Shows
The feature at the center is Nunatak Zaterjavshijsja, a rocky peak that interrupts the flow of ice streaming northeast toward the ocean. When ice hits an immovable object, it does not flow around it cleanly. It cracks. Deep fractures called crevasses spiderweb across the surface, and in this image they appear as sharp green lines cutting through softer magenta and white terrain.
The image was produced in August 2025 using NISAR's L-band radar, which transmits horizontally polarized microwaves toward Earth and reads how they bounce back. The colors tell a physical story:
- Magenta signals returned with horizontal polarization, indicating smooth, regular ice surfaces.
- Green shows vertical polarization, which occurs when radar waves refract through ice or scatter off irregular surfaces like crevasses, a process called volume scattering.
- White marks areas where both signal types scatter back strongly, suggesting a blend of surface and volume effects.
Why This Matters
NISAR is the first satellite to carry two synthetic aperture radar instruments at different wavelengths. The L-band SAR and its 39-foot (12-meter) antenna reflector, the largest NASA has ever launched, were provided by NASA's Jet Propulsion Laboratory, which manages the U.S. component through Caltech. ISRO supplied the spacecraft bus and the S-band SAR.
This dual-frequency approach lets scientists see through clouds and darkness to measure changes in Earth's surface with extraordinary precision. For Antarctica, that means tracking how ice flows, where it fractures, and how those fractures evolve over time. The "hummingbird" is not just a pretty picture. It is a data point in the effort to understand how Antarctica's ice sheets respond to a warming climate, and how quickly that ice might end up in the ocean.