NISAR, depicted in this artist’s concept, uses two radar systems to monitor changes in nearly all of Earth’s land and ice surfaces. The satellite marks the first time that the U.S. and Indian space agencies have collaborated on developing hardware for an Earth observation mission.Credit: NASA/JPL-California Institute of Technology
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NISAR, depicted in this artist’s concept, uses two radar systems to monitor changes in nearly all of Earth’s land and ice surfaces. The satellite marks the first time that the U.S. and Indian space agencies have collaborated on developing hardware for an Earth observation mission.Credit: NASA/JPL-California Institute of Technology
NISAR, a radar satellite soon to be launched by NASA and the Indian Space Research Organization (ISRO), will measure several important Earth vital signs, from the health of wetlands to ground deformation caused by volcanoes to the dynamics of land and sea ice. Measure.
This last feature will help researchers uncover how small-scale processes can cause large changes in the ice sheets covering Antarctica and Greenland, as well as mountain glaciers and sea ice around the world. Helpful.
NISAR, short for NASA-ISRO Synthetic Aperture Radar, provides the most comprehensive picture to date of the movement and deformation of frozen surfaces in Earth’s ice and snow-covered environment, collectively known as the cryosphere. Offers.
“The thermostat is set higher on our planet, and Earth’s ice is responding by accelerating its movement and melting faster,” said Alex Gardner, a glaciologist at NASA’s Jet Propulsion Laboratory in Southern California. ” “We need a deeper understanding of the processes that are taking place, and NISAR will provide measurements for that.”
Scheduled to be launched in 2024 by ISRO in southern India, NISAR will observe nearly all of Earth’s land and ice surfaces twice every 12 days. The satellite’s unique insight into Earth’s cryosphere comes from the combined use of two radars: a 10-inch (25-centimeter) L-band system and a 4-inch (10-centimeter) S-band system. You can get it with .
The L-band can be seen through the snow, allowing scientists to more accurately track the movement of the ice underneath, while the S-band is more sensitive to moisture in the snow, which indicates melting. Both signals penetrate clouds and darkness, allowing observations during months of extreme winter nights.
“Time-lapse video” of the ice sheet
NISAR’s orientation in orbit allows it to collect data from deep within and close to the South Pole, unlike other large imaging radar satellites that cover more of the North Pole.
The Antarctic ice sheet contains Earth’s largest reservoir of frozen fresh water, and the rate at which it is likely to be lost represents the greatest uncertainty in sea level rise projections. Expanding NISAR’s coverage will be critical to studying the movement of ice flowing from the highlands of central Antarctica toward the ocean.
The measurements will also allow scientists to study in detail what happens where ice and ocean meet. For example, if parts of an ice sheet lie below sea level, salt water can seep beneath the ice, increasing melting and instability. Antarctica and Greenland also have ice shelves (ice blocks that extend from the land and float in the ocean), which thin and crumble as icebergs break off. Ice shelves help prevent land-based glaciers from sliding into the ocean. When they decrease, glaciers can flow faster and collapse.
Ice loss in Antarctica and Greenland has accelerated since the 1990s, and there is uncertainty about how fast each will continue to retreat. NISAR improves horizontal and vertical perspectives on these changes.
“NISAR provides consistent time-lapse footage of its movement, so we can understand how and why it’s changing, and how it might change in the future,” said Ian Joggin, a glaciologist at the University of Washington in Seattle. “We can more accurately predict whether the situation will change.” NISAR cryosphere leader.
Glaciers, water supply and flooding in mountain areas
The satellite will also track changes in Earth’s mountain glaciers. Their melting has contributed to about a third of the sea level rise seen since the 1960s, and climate-induced changes in freezing and thawing patterns can affect water supplies for downstream populations. there is.
In the Himalayas, NISAR’s all-weather capabilities will help researchers monitor how much water is stored in glacial lakes. This is essential for assessing the risk of catastrophic flooding.
“The beauty and challenge of the Himalayas lies in the clouds,” says Sushil Kumar Singh, a glaciologist at the ISRO Space Applications Center in Ahmedabad, India. “NISAR allows us to obtain more continuous and complete data sets that are not possible with instruments that use visible light.”
Dynamics of sea ice near the 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. They also reflect sunlight and keep the Earth cool through the albedo effect.
Arctic sea ice has been declining for decades as rising ocean and air temperatures lead to more melting. Because much of its surface is exposed to sunlight, the Arctic Ocean gains and retains more heat in the summer, and takes longer to cool. That means less ice forms in the winter and melts faster the following summer, said Ben Holt, a sea ice scientist at JPL.
NISAR, which will cover more of Antarctica than any previous radar mission, will open up new insights around Antarctica, where sea ice has remained largely stable until the past few years.reached record low In 2023.
