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By NASA
6 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater)
The SWOT satellite is helping scientists size up flood waves on waterways like the Yellowstone River, pictured here in October 2024 in Montana. SWOT measures the height of surface waters, including the ocean, and hundreds of thousands of rivers, lakes, and reservoirs in the U.S. alone.NPS In a first, researchers from NASA and Virginia Tech used satellite data to measure the height and speed of potentially hazardous flood waves traveling down U.S. rivers. The three waves they tracked were likely caused by extreme rainfall and by a loosened ice jam. While there is currently no database that compiles satellite data on river flood waves, the new study highlights the potential of space-based observations to aid hydrologists and engineers, especially those working in communities along river networks with limited flood control structures such as levees and flood gates.
Unlike ocean waves, which are ordinarily driven by wind and tides, and roll to shore at a steady clip, river waves (also called flood or flow waves) are temporary surges stretching tens to hundreds of miles. Typically caused by rainfall or seasonal snowmelt, they are essential to shuttling nutrients and organisms down a river. But they can also pose hazards: Extreme river waves triggered by a prolonged downpour or dam break can produce floods.
“Ocean waves are well known from surfing and sailing, but rivers are the arteries of the planet. We want to understand their dynamics,” said Cedric David, a hydrologist at NASA’s Jet Propulsion Laboratory in Southern California and a coauthor of a new study published May 14 in Geophysical Research Letters.
SWOT is depicted in orbit in this artist’s concept, with sunlight glinting off one of its solar panels and both antennas of its key instrument — the Ka-band Radar Interferometer (KaRIn) — extended. The antennas collect data along a swath 30 miles (50 kilometers) wide on either side of the satellite.CNES Measuring Speed and Size
To search for river waves for her doctoral research, lead author Hana Thurman of Virginia Tech turned to a spacecraft launched in 2022. The SWOT (Surface Water and Ocean Topography) satellite is a collaboration between NASA and the French space agency CNES (Centre National d’Études Spatiales). It is surveying the height of nearly all of Earth’s surface waters, both fresh and salty, using its sensitive Ka-band Radar Interferometer (KaRIn). The instrument maps the elevation and width of water bodies by bouncing microwaves off the surface and timing how long the signal takes to return.
“In addition to monitoring total storage of waters in lakes and rivers, we zoom in on dynamics and impacts of water movement and change,” said Nadya Vinogradova Shiffer, SWOT program scientist at NASA Headquarters in Washington.
Thurman knew that SWOT has helped scientists track rising sea levels near the coast, spot tsunami slosh, and map the seafloor, but could she identify river height anomalies in the data indicating a wave on the move?
She found that the mission had caught three clear examples of river waves, including one that arose abruptly on the Yellowstone River in Montana in April 2023. As the satellite passed overhead, it observed a 9.1-foot-tall (2.8-meter-tall) crest flowing toward the Missouri River in North Dakota. It was divided into a dramatic 6.8-mile-long (11-kilometer-long) peak followed by a more drawn‐out tail. These details are exciting to see from orbit and illustrate the KaRIn instrument’s uniquely high spatial resolution, Thurman said.
Sleuthing through optical Sentinel-2 imagery of the area, she determined that the wave likely resulted from an ice jam breaking apart upstream and releasing pent-up water.
The other two river waves that Thurman and the team found were triggered by rainfall runoff. One, spotted by SWOT starting on Jan. 25, 2024, on the Colorado River south of Austin, Texas, was associated with the largest flood of the year on that section of river. Measuring over 30 feet (9 meters) tall and 166 miles (267 kilometers) long, it traveled around 3.5 feet (1.07 meters) per second for over 250 miles (400 kilometers) before discharging into Matagorda Bay.
The other wave originated on the Ocmulgee River near Macon, Georgia, in March 2024. Measuring over 20 feet (6 meters) tall and extending more than 100 miles (165 kilometers), it traveled about a foot (0.33 meters) per second for more than 124 miles (200 kilometers).
“We’re learning more about the shape and speed of flow waves, and how they change along long stretches of river,” Thurman said. “That could help us answer questions like, how fast could a flood get here and is infrastructure at risk?”
Complementary Observations
Engineers and water managers measuring river waves have long relied on stream gauges, which record water height and estimate discharge at fixed points along a river. In the United States, stream gauge networks are maintained by agencies including the U.S. Geological Survey. They are sparser in other parts of the world.
“Satellite data is complementary because it can help fill in the gaps,” said study supervisor George Allen, a hydrologist and remote sensing expert at Virginia Tech.
If stream gauges are like toll booths clocking cars as they pass, SWOT is like a traffic helicopter taking snapshots of the highway.
The wave speeds that SWOT helped determine were similar to those calculated using gauge data alone, Allen said, showing how the satellite could help monitor waves in river basins without gauges. Knowing where and why river waves develop can help scientists tracking changing flood patterns around the world.
Orbiting Earth multiple times each day, SWOT is expected to observe some 55% of large-scale floods at some stage in their life cycle. “If we see something in the data, we can say something,” David said of SWOT’s potential to flag dangerous floods in the making. “For a long time, we’ve stood on the banks of our rivers, but we’ve never seen them like we are now.”
More About SWOT
The SWOT satellite was jointly developed by NASA and CNES, with contributions from the Canadian Space Agency (CSA) and the UK Space Agency. NASA’s Jet Propulsion Laboratory, managed for the agency by Caltech in Pasadena, California, leads the U.S. component of the project. For the flight system payload, NASA provided the Ka-band radar interferometer (KaRIn) instrument, a GPS science receiver, a laser retroreflector, a two-beam microwave radiometer, and NASA instrument operations. The Doppler Orbitography and Radioposition Integrated by Satellite system, the dual frequency Poseidon altimeter (developed by Thales Alenia Space), the KaRIn radio-frequency subsystem (together with Thales Alenia Space and with support from the UK Space Agency), the satellite platform, and ground operations were provided by CNES. The KaRIn high-power transmitter assembly was provided by CSA.
News Media Contacts
Jane J. Lee / Andrew Wang
Jet Propulsion Laboratory, Pasadena, Calif.
818-354-0307 / 626-379-6874
Written by Sally Younger
2025-074
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Last Updated May 21, 2025 Related Terms
SWOT (Surface Water and Ocean Topography) Jet Propulsion Laboratory Explore More
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By NASA
6 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater)
Sunlight reflects off the ocean surface near Norfolk, Virginia, in this 1991 space shuttle image, highlighting swirling patterns created by features such as internal waves, which are produced when the tide moves over underwater features. Data from the international SWOT mission is revealing the role of smaller-scale waves and eddies.NASA The international mission collects two-dimensional views of smaller waves and currents that are bringing into focus the ocean’s role in supporting life on Earth.
Small things matter, at least when it comes to ocean features like waves and eddies. A recent NASA-led analysis using data from the SWOT (Surface Water and Ocean Topography) satellite found that ocean features as small as a mile across potentially have a larger impact on the movement of nutrients and heat in marine ecosystems than previously thought.
Too small to see well with previous satellites but too large to see in their entirety with ship-based instruments, these relatively small ocean features fall into a category known as the submesoscale. The SWOT satellite, a joint effort between NASA and the French space agency CNES (Centre National d’Études Spatiales), can observe these features and is demonstrating just how important they are, driving much of the vertical transport of things like nutrients, carbon, energy, and heat within the ocean. They also influence the exchange of gases and energy between the ocean and atmosphere.
“The role that submesoscale features play in ocean dynamics is what makes them important,” said Matthew Archer, an oceanographer at NASA’s Jet Propulsion Laboratory in Southern California. Some of these features are called out in the animation below, which was created using SWOT sea surface height data.
This animation shows small ocean features — including internal waves and eddies — derived from SWOT observations in the Indian, Atlantic, and Pacific oceans, as well as the Mediterranean Sea. White and lighter blue represent higher ocean surface heights compared to darker blue areas. The purple colors shown in one location represent ocean current speeds.
NASA’s Scientific Visualization Studio “Vertical currents move heat between the atmosphere and ocean, and in submesoscale eddies, can actually bring up heat from the deep ocean to the surface, warming the atmosphere,” added Archer, who is a coauthor on the submesoscale analysis published in April in the journal Nature. Vertical circulation can also bring up nutrients from the deep sea, supplying marine food webs in surface waters like a steady stream of food trucks supplying festivalgoers.
“Not only can we see the surface of the ocean at 10 times the resolution of before, we can also infer how water and materials are moving at depth,” said Nadya Vinogradova Shiffer, SWOT program scientist at NASA Headquarters in Washington.
Fundamental Force
Researchers have known about these smaller eddies, or circular currents, and waves for decades. From space, Apollo astronauts first spotted sunlight glinting off small-scale eddies about 50 years ago. And through the years, satellites have captured images of submesoscale ocean features, providing limited information such as their presence and size. Ship-based sensors or instruments dropped into the ocean have yielded a more detailed view of submesoscale features, but only for relatively small areas of the ocean and for short periods of time.
The SWOT satellite measures the height of water on nearly all of Earth’s surface, including the ocean and freshwater bodies, at least once every 21 days. The satellite gives researchers a multidimensional view of water levels, which they can use to calculate, for instance, the slope of a wave or eddy. This in turn yields information on the amount of pressure, or force, being applied to the water in the feature. From there, researchers can figure out how fast a current is moving, what’s driving it and —combined with other types of information — how much energy, heat, or nutrients those currents are transporting.
“Force is the fundamental quantity driving fluid motion,” said study coauthor Jinbo Wang, an oceanographer at Texas A&M University in College Station. Once that quantity is known, a researcher can better understand how the ocean interacts with the atmosphere, as well as how changes in one affect the other.
Prime Numbers
Not only was SWOT able to spot a submesoscale eddy in an offshoot of the Kuroshio Current — a major current in the western Pacific Ocean that flows past the southeast coast of Japan — but researchers were also able to estimate the speed of the vertical circulation within that eddy. When SWOT observed the feature, the vertical circulation was likely 20 to 45 feet (6 to 14 meters) per day.
This is a comparatively small amount for vertical transport. However, the ability to make those calculations for eddies around the world, made possible by SWOT, will improve researchers’ understanding of how much energy, heat, and nutrients move between surface waters and the deep sea.
Researchers can do similar calculations for such submesoscale features as an internal solitary wave — a wave driven by forces like the tide sloshing over an underwater plateau. The SWOT satellite spotted an internal wave in the Andaman Sea, located in the northeastern part of the Indian Ocean off Myanmar. Archer and colleagues calculated that the energy contained in that solitary wave was at least twice the amount of energy in a typical internal tide in that region.
This kind of information from SWOT helps researchers refine their models of ocean circulation. A lot of ocean models were trained to show large features, like eddies hundreds of miles across, said Lee Fu, SWOT project scientist at JPL and a study coauthor. “Now they have to learn to model these smaller scale features. That’s what SWOT data is helping with.”
Researchers have already started to incorporate SWOT ocean data into some models, including NASA’s ECCO (Estimating the Circulation and Climate of the Ocean). It may take some time until SWOT data is fully a part of models like ECCO. But once it is, the information will help researchers better understand how the ocean ecosystem will react to a changing world.
More About SWOT
The SWOT satellite was jointly developed by NASA and CNES, with contributions from the Canadian Space Agency (CSA) and the UK Space Agency. Managed for NASA by Caltech in Pasadena, California, JPL leads the U.S. component of the project. For the flight system payload, NASA provided the Ka-band radar interferometer (KaRIn) instrument, a GPS science receiver, a laser retroreflector, a two-beam microwave radiometer, and NASA instrument operations. The Doppler Orbitography and Radioposition Integrated by Satellite system, the dual frequency Poseidon altimeter (developed by Thales Alenia Space), the KaRIn radio-frequency subsystem (together with Thales Alenia Space and with support from the UK Space Agency), the satellite platform, and ground operations were provided by CNES. The KaRIn high-power transmitter assembly was provided by CSA.
To learn more about SWOT, visit:
https://swot.jpl.nasa.gov
News Media Contacts
Jane J. Lee / Andrew Wang
Jet Propulsion Laboratory, Pasadena, Calif.
626-491-1943 / 626-379-6874
jane.j.lee@jpl.nasa.gov / andrew.wang@jpl.nasa.gov
2025-070
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Last Updated May 15, 2025 Related Terms
SWOT (Surface Water and Ocean Topography) Jet Propulsion Laboratory Oceanography Oceans Explore More
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By European Space Agency
Image: Copernicus Sentinel-1 captured this radar image over French Guiana – home to Europe’s Spaceport in Kourou, where ESA’s Biomass mission is being prepared for liftoff on 29 April onboard a Vega-C rocket. View the full article
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By NASA
3 Min Read NASA’s IMAP Arrives at NASA Marshall For Testing in XRCF
On March 18, NASA’s IMAP (Interstellar Mapping and Acceleration Probe) arrived at NASA’s Marshall Space Flight Center in Huntsville, Alabama, for thermal vacuum testing at the X-ray and Cryogenic Facility, which simulates the harsh conditions of space.
The IMAP mission is a modern-day celestial cartographer that will map the solar system by studying the heliosphere, a giant bubble created by the Sun’s solar wind that surrounds our solar system and protects it from harmful interstellar radiation.
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NASA’s IMAP mission being loaded into the thermal vacuum chamber of NASA Marshall Space Flight Center’s X-Ray and Cryogenic Facility (XRCF) in Huntsville, Alabama. IMAP arrived at Marshall March 18 and was loaded into the chamber March 19.Credit: NASA/Johns Hopkins APL/Princeton/Ed Whitman Testing performed in the X-ray and Cryogenic Facility will help to assess the spacecraft before its journey toward the Sun. The IMAP mission will orbit the Sun at a location called Lagrange Point 1 (L1), which is about one million miles from Earth towards the Sun. From this location, IMAP can measure the local solar wind and scan the distant heliosphere without background from planets and their magnetic fields. The mission will use its suite of ten instruments to map the boundary of the heliosphere, analyze the composition of interstellar particles that make it through, and investigate how particles change as they move through the solar system.
Furthermore, IMAP will maintain a continuous broadcast of near real-time space weather data from five instruments aboard IMAP that will be used to test new space weather prediction models and improve our understanding of effects impacting our human exploration of space.
Team members from Marshall Space Flight Center in Huntsville, Alabama, install IMAP into the XRCF’s chamber dome before the start of the thermal vacuum test. NASA/Johns Hopkins APL/Princeton/Ed Whitman While inside the Marshall facility, the spacecraft will undergo dramatic temperature changes to simulate the environment during launch, on the journey toward the Sun, and at its final orbiting point. The testing facility has multiple capabilities including a large thermal vacuum chamber which simulates the harsh conditions of space such as extreme temperatures and the near-total absence of an atmosphere. Simulating these conditions before launch allow scientists and engineers to identify successes and potential failures in the design of the spacecraft.
Team members from Marshall Space Flight Center in Huntsville, Alabama work to close the chamber door of the XRCF for IMAP testing. The chamber is 20 feet in diameter and 60 feet long making it one of the largest across NASA. NASA/Johns Hopkins APL/Princeton/Ed Whitman “The X-ray and Cryogenic Facility was an ideal testing location for IMAP given the chamber’s size, availability, and ability to meet or exceed the required test parameters including strict contamination control, shroud temperature, and vacuum level,” said Jeff Kegley, chief of Marshall’s Science Test Branch.
The facility’s main chamber is 20 feet in diameter and 60 feet long, making it the 5th largest thermal vacuum chamber at NASA. It’s the only chamber that is adjoined to an ISO 6 cleanroom — a controlled environment that limits the number and size of airborne particles to minimize contamination.
The IMAP mission will launch on a SpaceX Falcon 9 rocket from NASA’s Kennedy Space Center in Florida, no earlier than September.
NASA’s IMAP mission was loaded into NASA Marshall’s XRCF thermal vacuum chamber where the spacecraft will undergo testing such as dramatic temperature changes to simulate the harsh environment of space. NASA/Johns Hopkins APL/Princeton/Ed Whitman Learn More about IMAP Media Contact:
Lane Figueroa
Marshall Space Flight Center
Huntsville, Alabama
256.544.0034
lane.e.figueroa@nasa.gov
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Last Updated Apr 11, 2025 Related Terms
Marshall Space Flight Center Goddard Space Flight Center Heliophysics Marshall Heliophysics & Planetary Science Marshall Science Research & Projects Marshall X-Ray & Cryogenic Facility The Sun The Sun & Solar Physics Explore More
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By NASA
NASA/Josh Valcarcel From the mountains of Turin to the deserts of Arizona, a core element of Gateway, humanity’s first lunar space station, is now one step closer to the Moon. As seen in this April 1, 2025, photo, HALO (Habitation and Logistics Outpost), Gateway’s first pressurized module and one of its foundational elements, recently arrived in Gilbert, Arizona, following its fabrication by Thales Alenia Space in Turin, Italy. Now on U.S. soil, the module will undergo final outfitting by primary contractor Northrop Grumman before it’s integrated with the Power and Propulsion Element at NASA’s Kennedy Space Center. Together, the two modules will launch to lunar orbit aboard a SpaceX Falcon Heavy rocket ahead of the Artemis IV mission.
HALO will support astronauts visiting Gateway and function as a command and control hub for the space station. It will feature docking ports for spacecraft such as NASA’s Orion, logistics vehicles and lunar landers, and provide data handling, energy storage, power distribution, thermal regulation, and communications and tracking capabilities.
HALO’s arrival marks a major milestone in the construction of Gateway, a cornerstone of NASA’s Artemis campaign to advance science and exploration on and around the Moon in preparation for the next giant leap: the first human missions to Mars.
Image credit: NASA/Josh Valcarcel
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