NISAR Satellite L-Band Radar Produces 'Hummingbird' Image of Antarctic Nunatak

Scientists have used data from the L-band radar on the U.S.-India NISAR (NASA-ISRO Synthetic Aperture Radar) satellite to produce an image of Nunatak Zaterjavshijsja, a mountaintop in East Antarctica, that resembles a hummingbird. The feature appears amid a stream of ice flowing northeast toward the ocean, according to a NASA Jet Propulsion Laboratory release.

The image was generated from measurements collected in August 2025 during testing of the satellite’s systems. As the glacier moves past the obstruction of the nunatak, the mountain’s topography creates stresses that heavily fracture the surrounding ice with deep crevasses. These appear as sharp green lines in the false-color image. Magenta portions represent more regular surfaces such as smooth ice, while white areas indicate a blend of scattering types, as described in the NASA Science photojournal entry.

The colors result from differences in how polarized microwave signals interact with and reflect from the ice. NISAR transmits radar waves with horizontal polarization over Antarctica. Signals returning with horizontal polarization, which likely bounced off smoother surfaces, appear magenta. Those returning with vertical polarization, associated with volume scattering from penetration into snow and ice or reflection from irregular surfaces like crevasse faces, appear green.

“First, it’s a beautiful image, with rich details of features that provide insights to how the glacier is moving. Then, because radar can often see through snow and deep into the ice, NISAR can observe fundamentally different properties of Antarctic ice than can be seen in optical imagery,” said Seongsu Jeong, the signal analysis engineer who produced the image at NASA’s Jet Propulsion Laboratory, in the JPL announcement. “With NISAR we’re seeing what’s hidden beneath the surface.”

An optical image from the Landsat 9 satellite of the same scene on Nov. 2, 2025, shows the area as almost entirely white with ice and snow, with only slight shadows and textures indicating the mountaintop and uneven ice, per the JPL report.

As of July 20, 2026, the public can access data from NISAR’s two radar instruments. U.S. and Indian teams are releasing processed files from the L-band and S-band radars on an ongoing basis. The U.S. side began continuous release of calibrated L-band products for measurements collected since June 17, with earlier data expected by year’s end. Data is available through the Alaska Satellite Facility Distributed Active Archive Center, according to JPL.

NISAR, launched on July 30, 2025, from India’s Satish Dhawan Space Centre, is the first free-flying space mission with both L-band and S-band synthetic aperture radar instruments. NASA’s Jet Propulsion Laboratory provided the L-band SAR and the 39-foot (12-meter) antenna reflector—the largest radar antenna reflector NASA has sent into space—while ISRO provided the spacecraft bus and S-band SAR. The longer-wavelength L-band can penetrate tree canopies and ice, complementing the S-band, as noted in the NASA photojournal description.

The mission monitors nearly all of Earth’s land- and ice-covered surfaces twice every 12 days, supporting studies of ice mass movement, ecosystems, and natural hazards. The Indian team has begun releasing S-band data via the Bhoonidhi portal. The satellite covers from near the South Pole to 77.5 degrees north latitude.

This early image demonstrates NISAR’s capacity for detailed, all-weather observations of polar ice dynamics that optical sensors cannot match under many conditions.