A New Eye in the Sky
NISAR, which stands for NASA-ISRO Synthetic Aperture Radar, is one of the most advanced Earth-observing satellites ever launched. A joint project between the US space agency, NASA, and the Indian Space Research Organisation (ISRO), it represents a major
milestone in international scientific partnership. Unlike a typical camera that needs light, NISAR uses a sophisticated radar system to bounce microwave signals off the Earth's surface and create incredibly detailed images, regardless of weather or time of day. The satellite carries two radar systems, NASA's L-band and ISRO's S-band, which work together to observe nearly all the planet's land and ice surfaces every 12 days. This constant stream of data, which was made publicly available in July 2026, is set to revolutionise our understanding of everything from earthquakes and deforestation to the movement of ice.
Seeing the Invisible
Antarctica can appear as a vast, white, and mostly featureless continent to a standard optical satellite. But NISAR’s power lies in its ability to see what's invisible. Its L-band radar waves can penetrate through snow and even into the upper layers of ice, revealing the complex structures and dynamics hidden beneath. Scientists analyse how these radar signals bounce back to the satellite. For example, signals that return with a horizontal orientation likely bounced off a smooth surface like flat ice, while signals that return with a vertical orientation may have scattered off the rough faces of deep cracks and crevasses. By colour-coding these different returns, scientists can create images that expose the true complexity of the ice sheet's structure.
The Antarctic 'Hummingbird'
One of the first stunning images from NISAR's Antarctic observations was nicknamed 'the hummingbird' by scientists. The image shows a feature in East Antarctica where a submerged mountain peak, known as a nunatak, obstructs the flow of a massive ice stream. As the ice flows around this obstacle, it is put under immense stress, causing it to fracture into a network of deep crevasses. When viewed through NISAR's radar, the pattern of these cracks remarkably resembles a giant hummingbird with its wings outstretched. While visually striking, the image is a powerful demonstration of the satellite's ability to map the stresses and strains within the ice, providing an unprecedented view of glacial movement.
Why Antarctica's Secrets Matter to India
The data NISAR is gathering from thousands of kilometres away in Antarctica has direct implications for India. The Antarctic and Greenland ice sheets hold the vast majority of the world's fresh water, and their melting is the single biggest driver of global sea-level rise. By tracking the velocity of glaciers and the stability of ice shelves with pinpoint accuracy, NISAR will provide crucial data to refine projections of sea-level rise. For a nation with over 7,500 kilometres of coastline and densely populated cities like Mumbai, Kolkata, and Chennai, understanding and preparing for even small increases in sea level is a critical national security and economic issue. The insights from this joint ISRO-NASA mission will be invaluable for climate adaptation and planning.
