The NASA-ISRO Synthetic Aperture Radar (NISAR) satellite has produced an image of a mountain peak in East Antarctica that scientists have nicknamed "the hummingbird." The image shows Nunatak Zaterjavshijsja, a mountaintop poking through a stream of ice flowing northeast toward the ocean, and was generated using data from the satellite's L-band radar instrument collected during systems testing. The satellite's L-band and S-band radar systems were powered on and passed checkouts following the deployment of its 12-meter antenna reflector on Aug. 15.
The colors in the image reflect differences in how polarized radar signals interact with the ice. L-band frequency ranges from 1 to 2 gigahertz and S-band from 2 to 4 gigahertz, and NISAR is the first satellite to use both microwave frequencies for radar observation. The 12-meter reflector, the observatory's most prominent feature, is made of gold-plated wire mesh that focuses radar signals emitted and received by an upward-facing feed, illuminating a 150-mile swath of ground during each transmission. A space-based radar without this synthetic aperture technique would need an antenna roughly 65,000 feet long to achieve the same image resolution NISAR produces with its 12-meter reflector.
NASA's contributions to the mission include the L-band SAR instrument, the deployable mesh reflector and boom, a high-capacity solid-state recorder of approximately 9 terabits, GPS, and a 3.5 Gbps Ka-band telecom system. The satellite launched from India's Satish Dhawan Space Centre on July 30, 2025, and was raised to its operational orbit of 464 miles on Aug. 26.
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