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. Both Antarctica and Greenland also have ice shelves – masses of ice that extend from land and float on the ocean – that are thinning and crumbling as icebergs break off. Ice shelves help keep glacial ice on the land from slipping into the ocean. If they are diminished, glaciers can flow and calve faster.
Ice losses on both Antarctica and Greenland have accelerated since the 1990s, and there’s uncertainty about how quickly each will continue to recede. NISAR will improve our horizontal and vertical views of these changes.
“NISAR will give us a consistent time-lapse movie of that motion, so we can understand how and why it’s changing and better predict how it will change into the future,” said Ian Joughin, a glaciologist at the University of Washington in Seattle and the NISAR cryosphere lead.
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Mountain Glaciers, Water Supply, and Flooding
The satellite will also track changes in Earth’s mountain glaciers. Their melting has contributed about a third of the sea level rise seen since the 1960s, and climate-driven changes to freezing and thawing patterns can affect the water supplies of downstream populations.
In the Himalayas, NISAR’s all-weather capability will help researchers monitor how much water is stored in , which is essential to assessing the risk of catastrophic floods.
“The beauty and the difficulty of the Himalayas are the clouds,” said Sushil Kumar Singh, a glaciologist at the ISRO Space Applications Centre in Ahmedabad, India. “With NISAR we will be able to get a more continuous and complete data set that would not be possible with instruments that use visible light.”
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Sea Ice Dynamics Near Both Poles
NISAR will also capture the movement and extent of sea ice in both hemispheres. Sea ice insulates the ocean from the air, reducing evaporation and heat loss to the atmosphere. It also reflects sunlight, keeping the planet cool through the albedo effect.
Arctic sea ice has been diminishing for decades as rising water and air temperatures have increased melting. With more of its surface exposed to sunlight, the Arctic Ocean gains and holds more heat in summer and takes longer to cool. This means less ice formation in winter and faster melting the next summer, said Ben Holt, a JPL sea-ice scientist.
With greater coverage of the Southern Ocean than any radar mission to date, NISAR will open new insights around Antarctica, where sea ice had mostly been more stable until the past few years. It reached a in 2023.
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More About the Mission
NISAR is an equal collaboration between NASA and ISRO and marks the first time the two agencies have cooperated on hardware development for an Earth-observing mission. NASA’s Jet Propulsion Laboratory, which is managed for the agency by Caltech in Pasadena, California, leads the U.S. component of the project and is providing the mission’s L-band SAR. NASA is also providing the radar reflector antenna, the deployable boom, a high-rate communication subsystem for science data, GPS receivers, a solid-state recorder, and payload data subsystem. U R Rao Satellite Centre (URSC) in Bengaluru, which leads the ISRO component of the mission, is providing the spacecraft bus, the launch vehicle, and associated launch services and satellite mission operations. ISRO’s Space Applications Centre in Ahmedabad is providing the S-band SAR electronics.
To learn more about NISAR, visit:
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