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NISAR<\/strong>, the soon-to-launch radar satellite from NASA<\/strong> and the Indian Space Research Organisation<\/strong>, will measure some key Earth vital signs, from the health of wetlands to ground deformation by volcanoes to the dynamics of land and sea ice.<\/p>\n This last capability will help researchers decipher how small-scale processes can cause monumental changes in the ice sheets covering Antarctica and Greenland, as well as on mountain glaciers and sea ice around the world.<\/p>\n Short for NASA-ISRO Synthetic Aperture Radar, NISAR will provide the most comprehensive picture to date of motion and deformation of frozen surfaces in Earth\u2019s ice- and snow-covered environments, collectively known as the cryosphere.<\/p>\n \u201cOur planet has the thermostat set on high, and Earth\u2019s ice is responding by speeding up its motion and melting faster,\u201d said Alex Gardner<\/strong>, a glaciologist at NASA\u2019s Jet Propulsion Laboratory in Southern California. \u201cWe need to better understand the processes at play, and NISAR will provide measurements to do that.\u201d<\/p>\n Set to be launched in 2024 by ISRO from southern India, NISAR will observe nearly all the planet\u2019s land and ice surfaces twice every 12 days. The satellite\u2019s unique insights into Earth\u2019s cryosphere will come from the combined use of two radars: an L-band system with a 10-inch (25-centimeter) wavelength and an S-band system with a 4-inch (10-centimeter) wavelength.<\/p>\n L-band can see through snow, helping scientists better track the motion of ice underneath, while S-band is more sensitive to snow moisture, which indicates melting. Both signals penetrate clouds and darkness, enabling observations during monthslong polar winter nights.<\/p>\n \u2018Time-Lapse Movie\u2019 of Ice Sheets<\/strong><\/p>\n NISAR\u2019s orientation in orbit will enable it to collect data from Antarctica\u2019s far interior, close to the South Pole \u2013 unlike other large imaging radar satellites, which have more extensively covered the Arctic.<\/p>\n Antarctica\u2019s ice sheets hold the planet\u2019s largest reservoir of frozen fresh water, and the rate at which it may lose ice represents the greatest uncertainty in sea level rise projections. NISAR\u2019s increased coverage will be crucial for studying the motion of ice flowing down from central Antarctica\u2019s high elevations toward the sea.<\/p>\n 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 \u2013 masses of ice that extend from land and float on the ocean \u2013 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.<\/p>\n Ice losses on both Antarctica and Greenland have accelerated since the 1990s, and there\u2019s uncertainty about how quickly each will continue to recede. NISAR will improve our horizontal and vertical views of these changes.<\/p>\n \u201cNISAR will give us a consistent time-lapse movie of that motion, so we can understand how and why it\u2019s changing and better predict how it will change into the future,\u201d said Ian Joughin<\/strong>, a glaciologist at the University of Washington in Seattle and the NISAR cryosphere lead.<\/p>\n Mountain Glaciers, Water Supply, and Flooding<\/strong><\/p>\n The satellite will also track changes in Earth\u2019s 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.<\/p>\n In the Himalayas, NISAR\u2019s all-weather capability will help researchers monitor how much water is stored in glacial lakes, which is essential to assessing the risk of catastrophic floods.<\/p>\n \u201cThe beauty and the difficulty of the Himalayas are the clouds,\u201d said Sushil Kumar Singh<\/strong>, a glaciologist at the ISRO Space Applications Centre in Ahmedabad, India. \u201cWith 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.\u201d<\/p>\n Sea Ice Dynamics Near Both Poles<\/strong><\/p>\n 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.<\/p>\n 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<\/strong>, a JPL sea-ice scientist.<\/p>\n 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 record low in 2023.<\/p>\n More About the Mission<\/strong><\/p>\n 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\u2019s 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\u2019s 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\u2019s Space Applications Centre in Ahmedabad is providing the S-band SAR electronics.<\/p>\n