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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.
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Jane J. Lee / Andrew Wang
Jet Propulsion Laboratory, Pasadena, Calif.
818-354-0307 / 626-379-6874
Written by Sally Younger
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Last Updated May 21, 2025 Related Terms
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By NASA
4 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater)
Spectrum is a shared resource. Since the discovery of radio waves and the invention of the telegraph, humanity has exponentially increased its use of the radio frequency (RF) spectrum. Consider how many wireless devices are around you right now. You’re probably reading this on a smartphone or laptop connected to the internet through Wi-Fi or 5G. You might be listening to music on Bluetooth headphones. If you are in a car or bus, the driver may be using signals from GPS satellites. To meet this increasing need, RF engineers and regulators continue to develop ways to enable users to share the same frequencies at the same time in the same place — think of modern cell phone technology. Avoiding or lessening interference between users requires regulators and users alike to maintain and enforce the ‘rules of the road’ that describe who can use which frequencies where, when, and how. NASA, like all other users, must comply with these regulations and collaborate with other users to ensure our use of the RF spectrum can continue and evolve.
Just as architects design taller buildings to accommodate more residences on the same plot of land, radio frequency engineers design methods to allow more users on the same frequency, at the same place and time.NASA Supporting and Protecting NASA’s Spectrum Users
NASA’s spectrum professionals work with users early in the project planning phase to understand the type, location, and duration of their data, and in turn determine what kind of antennas, transmitters, and receivers will be required. With that information, a spectrum manager helps to define the spectrum requirements, such as bandwidths, modulation, and other technical characteristics of the radio signals to be used. Understanding a project’s objectives helps define the appropriate service allocation and potential frequency ranges.
Once these spectrum requirements are determined, NASA’s spectrum professionals work with other relevant spectrum users within and beyond NASA to coordinate the use of the spectrum.
In the unfortunate event of harmful RF interference, working to identify, resolve, and report the interference is another critical function of NASA’s spectrum professionals. For example as Jeff Hayes — NASA’s current SCaN (Space Communications and Navigation) Program liaison to the Science Mission Directorate and the former program executive for operating missions in the Heliophysics and Astrophysics Divisions — recounts, “The NICER (Neutron Star Interior Composition Explorer) observatory did actually experience bouts of RF interference over certain parts of the world. As NICER uses GPS to understand where it is pointing to in the sky, interference can make the location information of the source imprecise, and that impacts the quality of the data collected. That data could potentially be attributed to the wrong star.”
When NASA identifies interference to a mission like NICER or to a device at an agency center or facility, NASA center and facility spectrum managers work to identify, resolve, and report the interference.
Identifying and reporting sources of interference helps to raise awareness of the impacts and causes of interference. When the sources of interference are international, which is especially common for space systems like NICER, SCaN’s spectrum management team works with U.S. regulators to report the incident to international regulators. These interference reports can be used to advocate for regulatory protections that help ensure the integrity of valuable science data and the safety of human spaceflight activities.
Advocating for NASA’s Current and Future Spectrum Use
NASA’s spectrum analysts and engineers perform analyses and simulations to support spectrum planning and management activities. For example, passive remote sensing instruments like the radiometer on the Soil Moisture Active Passive mission detect natural energy (radiation) emitted or reflected by an object or scene being observed. This energy is much fainter than human-generated radio signals and require highly sensitive radiometers that are susceptible to interference from more powerful signals. The spectrum management team works to ensure regulatory protections are in place and followed to ensure the integrity of NASA’s scientific missions.
Sometimes NASA’s future missions envision new ways and places to use radio waves. For example, when NASA’s Artemis campaign began taking steps to return humans to the Moon, SCaN’s spectrum professionals began working with other stakeholders to develop a RF architecture that enables the use of radio waves for science data, communications, positioning, navigation, and timing while also limiting the risk of interference with systems on or orbiting Earth. NASA’s spectrum professionals further the agency’s spectrum management goals and objectives by analyzing potential changes in international or domestic regulations and proposing technical solutions that promote collaborative spectrum use with both foreign and domestic partners.
NASA’s technical expertise is critical to ensuring domestic and international regulators are well informed as they develop new or revised regulations that effectively enable the exciting innovation and exploration central to NASA’s mission.
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Last Updated Apr 23, 2025 Related Terms
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By NASA
Explore This Section Science Science Activation Connected Learning Ecosystems:… Overview Learning Resources Science Activation Teams SME Map Opportunities More Science Activation Stories Citizen Science 5 min read
Connected Learning Ecosystems: Educators Gather to Empower Learners and Themselves
Many educators would agree that despite working and communicating with dozens, even hundreds, of people each year, the role can feel isolating. Learners come and go, leaving educators to question: Was anything retained? Will they take this knowledge home? Will they share it at their after-school activities? How will it ultimately impact their lives and perspectives? What some educators may not fully realize is that they are not alone in their efforts. Their classroom or alternate education space is but one step along a learning pathway that winds through an entire network of educators. Learning pathways take many forms, but are most effective when each stop along the path builds upon what a learner has experienced during previous stops. These networks of educators, known as Connected Learning Ecosystems (CLEs), exist wherever learning takes place. Simply put, CLEs are made up of all the people involved at any point in a youth’s learning journey.
With this in mind, the NASA Science Activation Program’s Learning Ecosystems Northeast (LENE) project has been working to connect and support the regional networks found throughout Maine and the Northeastern United States, with a shared focus on Science, Technology, Education, and Mathematics (STEM) education. This inspiring community includes classroom teachers, librarians, 4-H staff, and land trust educators, to name a few, all collaborating to advance education about our changing planet and improve data literacy across a variety of learning environments.
In support of these regional networks, LENE hosts a Connected Learning Ecosystems Gathering twice each year, a multi-day event designed to unite educators who have these shared STEM education goals. These gatherings provide opportunities to reflect on past successes and plan future projects, ultimately benefiting not just the educators, but every learner they reach. They also help strengthen and amplify the lasting and positive impact these educators have on the lives of the youth they support.
This year’s Gathering took place in late February in Orono, ME at the University of Maine (a LENE project partner). The event featured hands-on science activities adaptable to various learning spaces, dedicated reflection time for educators, and collaborative planning sessions to design cross-context learning opportunities for local youth. Participants engaged with NASA’s Global Learning and Observations to Benefit the Environment (GLOBE) Program, supported by Jen Bourgeault (GLOBE US Country Coordinator) and Haley Wicklein (GLOBE Assistant US Country Coordinator), who facilitated field data collection and program exploration. NASA Subject Matter Expert Shawn Laatsch from UMaine’s Versant Planetarium led an immersive evening show on the molecular world inside the human body and also previewed other potential field trip shows for students. One highlight of the Gathering was a presentation on climate science and ice core collection by experts Sean Birkel and Daniel Dixon from UMaine’s Climate Change Institute. Educators also participated in a hands-on activity using model ice cores designed by project partner UMaine 4-H. Rounding out the two-day event were deep-dive sessions into various connected learning projects, where educators shared their insights, from idea formation to project execution and reflection.
One educator shared about their experience: “I just want the leadership team to know how grateful I am to be part of this community. As a veteran teacher of 28 years, this is by far the BEST workshop I have ever attended. The passion for evidence-based science among this group is incredible. I feel seen and connected in ways that other workshops have never made possible. I will definitely be a lifelong member and will be bringing more people to CLE workshops. Thank you for making this meaningful and valuable.”
Another educator shared, “During the gathering, I had the opportunity to strengthen existing relationships and make new connections within [my region]. I engaged in insightful conversations with several individuals, discussing shared interests in environmental education, science literacy, and place-based learning…. From these connections, I hope to foster new collaborations that enhance environmental literacy opportunities for students and communities. By working together, I believe we can create interdisciplinary programs that bridge science, sustainability, and civic engagement in meaningful ways.”
Despite the support of regional groups, feelings of isolation persist, particularly in rural areas. These biannual gatherings serve as powerful reminders that this work is happening statewide, and that Connected Learning Ecosystems help establish and strengthen a network to bridge the distance between educators.
These Gatherings are part of ongoing programming organized by Learning Ecosystems Northeast, based at the Gulf of Maine Research Institute, that fosters peer communities across the Northeast through which teachers, librarians, and out-of-school educators can collaborate to expand opportunities for youth to engage in data-driven climate investigations and integrate in- and out-of-school learning.
The Learning Ecosystems Northeast project is supported by NASA under cooperative agreement award number NNX16AB94A and is part of NASA’s Science Activation Portfolio. Learn more about Learning Ecosystems Northeast: https://www.learningecosystemsnortheast.org/
The whole group discussing their findings after a GLOBE fieldwork activity. Share
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Last Updated Apr 07, 2025 Editor NASA Science Editorial Team Related Terms
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Explore This Section Exoplanets Home Exoplanets Overview Exoplanets Facts Types of Exoplanets Stars What is the Universe Search for Life The Big Questions Are We Alone? Can We Find Life? The Habitable Zone Why We Search Target Star Catalog Discoveries Discoveries Dashboard How We Find and Characterize Missions People Exoplanet Catalog Immersive The Exoplaneteers Exoplanet Travel Bureau 5 Ways to Find a Planet Strange New Worlds Universe of Monsters Galaxy of Horrors News Stories Blog Resources Get Involved Glossary Eyes on Exoplanets Exoplanet Watch More Multimedia ExEP This artist’s concept pictures the planets orbiting Barnard’s Star, as seen from close to the surface of one of them. Image credit: International Gemini Observatory/NOIRLab/NSF/AURA/P. Marenfeld The Discovery
Four rocky planets much smaller than Earth orbit Barnard’s Star, the next closest to ours after the three-star Alpha Centauri system. Barnard’s is the nearest single star.
Key Facts
Barnard’s Star, six light-years away, is notorious among astronomers for a history of false planet detections. But with the help of high-precision technology, the latest discovery — a family of four — appears to be solidly confirmed. The tiny size of the planets is also remarkable: Capturing evidence of small worlds at great distance is a tall order, even using state-of-the-art instruments and observational techniques.
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Watching for wobbles in the light from a star is one of the leading methods for detecting exoplanets — planets orbiting other stars. This “radial velocity” technique tracks subtle shifts in the spectrum of starlight caused by the gravity of a planet pulling its star back and forth as the planet orbits. But tiny planets pose a major challenge: the smaller the planet, the smaller the pull. These four are each between about a fifth and a third as massive as Earth. Stars also are known to jitter and quake, creating background “noise” that potentially could swamp the comparatively quiet signals from smaller, orbiting worlds.
Astronomers measure the back-and-forth shifting of starlight in meters per second; in this case the radial velocity signals from all four planets amount to faint whispers — from 0.2 to 0.5 meters per second (a person walks at about 1 meter per second). But the noise from stellar activity is nearly 10 times larger at roughly 2 meters per second.
How to separate planet signals from stellar noise? The astronomers made detailed mathematical models of Barnard’s Star’s quakes and jitters, allowing them to recognize and remove those signals from the data collected from the star.
The new paper confirming the four tiny worlds — labeled b, c, d, and e — relies on data from MAROON-X, an “extreme precision” radial velocity instrument attached to the Gemini Telescope on the Maunakea mountaintop in Hawaii. It confirms the detection of the “b” planet, made with previous data from ESPRESSO, a radial velocity instrument attached to the Very Large Telescope in Chile. And the new work reveals three new sibling planets in the same system.
Fun Facts
These planets orbit their red-dwarf star much too closely to be habitable. The closest planet’s “year” lasts a little more than two days; for the farthest planet, it’s is just shy of seven days. That likely makes them too hot to support life. Yet their detection bodes well in the search for life beyond Earth. Scientists say small, rocky planets like ours are probably the best places to look for evidence of life as we know it. But so far they’ve been the most difficult to detect and characterize. High-precision radial velocity measurements, combined with more sharply focused techniques for extracting data, could open new windows into habitable, potentially life-bearing worlds.
Barnard’s star was discovered in 1916 by Edward Emerson Barnard, a pioneering astrophotographer.
The Discoverers
An international team of scientists led by Ritvik Basant of the University of Chicago published their paper on the discovery, “Four Sub-Earth Planets Orbiting Barnard’s Star from MAROON-X and ESPRESSO,” in the science journal, “The Astrophysical Journal Letters,” in March 2025. The planets were entered into the NASA Exoplanet Archive on March 13, 2025.
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Last Updated Apr 01, 2025 Related Terms
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