Science & Technology

Indo-US satellite NISAR to study Earth’s cryospheric changes, will help in natural resource, hazard management

The satellite's all-weather capability is particularly beneficial for monitoring regions like the Himalayas, where cloud cover can hinder data collection

 
By Preetha Banerjee
Published: Friday 12 January 2024
An artist's rendition of the two-radar satellite Nisar. Source: NASA / JPL-Caltech

The United States National Aeronautics and Space Administration (NASA) and Indian Space Research Organisation (ISRO) have collaborated to create NASA-ISRO Synthetic Aperture Radar (NISAR), according to an announcement by NASA. The radar satellite set to launch this year aims to monitor changes in Earth’s frozen regions, including ice sheets, glaciers and sea ice. 

NISAR will employ advanced radar technology to monitor changes across Earth’s land and ice surfaces, particularly focusing on the dynamics of ice shelves in polar regions. This initiative comes at a crucial time, as recent satellite imagery from East Antarctica has shown significant glacial collapse, highlighting the urgent need for detailed monitoring.

It will employ two radar systems, an L-band and an S-band, to penetrate clouds and darkness, offering comprehensive data even during polar winter nights. 

This mission is distinguished by its ability to track a variety of Earth’s vital signs, ranging from the health of wetlands to the impacts of deforestation and natural hazards, NASA noted in the official statement. 

The satellite will provide detailed observations of these regions, helping to understand the impacts of climate change. The L-band radar is particularly adept at penetrating snow, offering insights into the movement of ice beneath, while the S-band radar focuses on snow moisture, indicating areas of melting. This will help gather comprehensive data even during polar winter nights. 

“Our planet’s ice is responding to the thermostat set on high by speeding up its motion and melting faster,” said Alex Gardner, a glaciologist at NASA’s Jet Propulsion Laboratory, in the NASA article. NISAR’s data will be instrumental in understanding these processes and their impact on global sea levels.

Set to be launched from southern India, NISAR will cover nearly all of the planet’s land and ice surfaces every 12 days. Its orientation in orbit will allow for data collection from the far interior of Antarctica, a region not extensively covered by other imaging radar satellites. This coverage is vital for understanding the movement of ice from central Antarctica and its implications for sea level rise.

The NASA blog mentioned: 

The measurements will also enable scientists to closely study what happens where ice and ocean meet. For example, when parts of an ice sheet sit on ground that is below sea level, saltwater can seep under the ice and increase melting and instability. 

The mission will also provide a ‘time-lapse movie’ of ice sheets, offering a consistent view of their motion, thus aiding in predictions of future changes. Ian Joughin, a glaciologist at the University of Washington and the NISAR cryosphere lead, emphasises the importance of this feature for understanding and predicting the dynamics of ice sheets.

Beyond polar ice, NISAR will track changes in mountain glaciers, which have significantly contributed to sea level rise since the 1960s. These glaciers play a critical role in the water supply for downstream populations, and their melting patterns directly impact the risk of catastrophic floods, especially in regions like the Himalayas.

The satellite’s all-weather capability is particularly beneficial for monitoring regions like the Himalayas, where cloud cover can hinder data collection. Sushil Kumar Singh, a glaciologist at ISRO’s Space Applications Centre, noted that NISAR will provide a more continuous and comprehensive data set than possible with instruments relying on visible light.

NISAR will also shed light on the dynamics of sea ice near both poles. The diminishing Arctic sea ice and the relatively stable, yet recently declining, Antarctic sea ice are critical to understanding global climate patterns. The mission’s extensive coverage of the Southern Ocean is unprecedented and will offer new insights into these crucial areas.

This mission represents a first-of-its-kind collaboration between NASA and ISRO in hardware development for an Earth-observing mission. NASA’s Jet Propulsion Laboratory will lead the US component and provide the mission’s L-band SAR. ISRO’s UR Rao Satellite Centre and Space Applications Centre will contribute the spacecraft bus, launch vehicle and S-band SAR electronics.

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