WASHINGTON: A joint US-India Earth-observation satellite has begun releasing data from both its radar instruments, offering scientists a new view of changes across the planet — including an Antarctic landscape that resembles a hummingbird.
Public access to data from the NASA-ISRO Synthetic Aperture Radar satellite, or NISAR, opened on July 20. Teams in the United States and India will continue releasing processed files from its L-band and S-band radars, NASA said in a media release.
The data can help researchers track the movement of land and ice, monitor forests and wetlands, and respond to hazards such as earthquakes and landslides.
The release comes days before the first anniversary of NISAR’s launch from India’s Satish Dhawan Space Centre on July 30, 2025. Since then, mission teams have calibrated the instruments, refined processing algorithms and monitored nearly all land and ice-covered surfaces twice every 12 days.
NASA released an early image on Tuesday showing Nunatak Zaterjavshijsja, a mountaintop in East Antarctica, rising amid ice flowing northeast towards the ocean. The fractured landscape forms the outline of what appears to be a hummingbird.
As the glacier moves around the mountain, the topography creates stress in the ice. Deep crevasses appear as sharp green lines in the radar image, while smoother ice surfaces appear magenta.
“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 Southern California.
“With NISAR we’re seeing what’s hidden beneath the surface.”
The image was generated from L-band measurements collected in August 2025 while US and Indian teams were testing the satellite’s systems.
Its colours reflect how polarised microwave signals interacted with the ice. Horizontally polarised returns, usually associated with smoother surfaces, appear magenta. Vertically polarised returns may have refracted after partly penetrating snow and ice, or scattered from irregular surfaces such as crevasse walls. Those areas appear green. White areas may indicate a strong blend of both types of scattering.
ISRO’s Space Applications Centre in Ahmedabad has begun releasing S-band data through the Bhoonidhi portal. The US side started continuously releasing calibrated L-band products collected since June 17. Earlier releases included sample products in January and thousands of pre-calibrated products in February.
The mission produces dozens of terabytes of science data each day. It scans from near the South Pole to 77.5 degrees north, above the Arctic Circle. Its 12-metre drum-shaped reflector is the largest radar antenna reflector NASA has sent into space.
NISAR is the first satellite mission jointly developed by NASA and ISRO. It builds on years of US-India civil space cooperation, including NASA instruments flown aboard India’s Chandrayaan-1 lunar mission.
Synthetic aperture radar can collect observations through cloud cover and darkness, unlike conventional optical instruments. That capability is widely used to detect gradual surface movement and rapid changes caused by earthquakes, landslides, floods and other natural events.
--IANS
