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Earth (ESD) Earth Explore Explore Earth Home Agriculture Air Quality Climate Change Freshwater Life on Earth Severe Storms Snow and Ice The Global Ocean Science at Work Earth Science at Work Technology and Innovation Powering Business Multimedia Image Collections Videos Data For Researchers About Us 5 Min Read NASA Data, Trainings Help Uruguay Navigate Drought
Uruguay’s Paso Severino Reservoir, the primary water source for Montevideo, on June 13, 2023, captured by Landsat 9. Credits:
NASA Earth Observatory/ Wanmei Liang Lee esta historia en español aquí.
NASA satellite data and trainings helped Uruguay create a drought-response tool that its National Water Authority now uses to monitor reservoirs and guide emergency decisions. A similar approach could be applied in the United States and other countries around the world.
From 2018 to 2023, Uruguay experienced its worst drought in nearly a century. The capital city of Montevideo, home to nearly 2 million people, was especially hard hit. By mid-2023, Paso Severino, the largest reservoir and primary water source for Montevideo, had dropped to just 1.7% of its capacity. As water levels declined, government leaders declared an emergency. They began identifying backup supplies and asked: Was there water left in other upstream reservoirs — mainly used for livestock and irrigation — that could help?
That’s when environmental engineer Tiago Pohren and his colleagues at the National Water Authority (DINAGUA – Ministry of Environment) turned to NASA data and trainings to build an online tool that could help answer that question and improve monitoring of the nation’s reservoirs.
“Satellite data can inform everything from irrigation scheduling in the Great Plains to water quality management in the Chesapeake Bay,” said Erin Urquhart, manager of the water resources program at NASA Headquarters in Washington. “NASA provides the reliable data needed to respond to water crises anywhere in the world.”
Learning to Detect Water from Space
The DINAGUA team learned about NASA resources during a 2022 workshop in Buenos Aires, organized by the Interagency Science and Applications Team (ISAT). Led by NASA, the U.S. Army Corps of Engineers, and the U.S. Department of State, the workshop focused on developing tools to help manage water in the La Plata River Basin, which spans multiple South American countries including Uruguay.
At the workshop, researchers from NASA introduced participants to methods for measuring water resources from space. NASA’s Applied Remote Sensing (ARSET) program also provided a primer on remote sensing principles.
DINAGUA team supervisor Jose Rodolfo Valles León asks a question during a 2022 workshop in Buenos Aires. Other members of the Uruguay delegation — Florencia Hastings, Vanessa Erasun Rodríguez de Líma, Vanessa Ferreira, and Teresa Sastre (current Director of DINAGUA) — sit in the row behind. Organization of American States “NASA doesn’t just deliver data,” said John Bolten, NASA’s lead scientist for ISAT and chief of the Hydrological Sciences Laboratory at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “We collaborate with our partners and local experts to translate the data into information that is useful, usable, and relevant. That kind of coordination is what makes NASA’s water programs so effective on the ground, at home and around the world.”
The DINAGUA team brought ideas and provided guidelines to Pohren for a tool that applies Landsat and Sentinel satellite imagery to detect changes in Uruguay’s reservoirs. Landsat, a joint NASA-U.S. Geological Survey mission, provides decades of satellite imagery to track changes in land and water. The Sentinel missions, a part of the European Commission managed Copernicus Earth Observation program and operated by ESA (the European Space Agency), provide complementary visible, infrared, and microwave imagery for surface water assessments.
From a young age, Pohren was familiar with water-related challenges, as floods repeatedly inundated his relatives’ homes in his hometown of Montenegro, Brazil. It was extra motivation for him as he scoured ARSET tutorials and taught himself to write computer code. The result was a monitoring tool capable of estimating the surface area of Uruguay’s reservoirs over time.
A screenshot of the reservoir monitoring tool shows the Paso Severino’s surface water coverage alongside time-series data tracking its variations. Tiago Pohren The tool draws on several techniques to differentiate the surface water extent of reservoirs. These techniques include three optical indicators derived from the Landsat 8 and Sentinel-2 satellites:
Normalized Difference Water Index, which highlights water by comparing how much green and near-infrared light is reflected. Water absorbs infrared light, so it stands out clearly from land. Modified Normalized Difference Water Index, which swaps near-infrared with shortwave infrared to improve the contrast and reduce errors when differentiating between water and built-up or vegetated areas. Automated Water Extraction Index, which combines four types of reflected light — green, near-infrared, and two shortwave infrared bands — to help separate water from shadows and other dark features. From Emergency Tool to Everyday Asset
In 2023, the DINAGUA team used Pohren’s tool to examine reservoirs located upstream from Montevideo’s drinking water intake. But the data told a tough story.
“There was water available in other reservoirs, but it was a very small amount compared to the water demand of the Montevideo metropolitan region,” Pohren said. Simulations showed that even if all of the water were released, most of it would not reach the water intake for Montevideo or the Paso Severino reservoir.
Despite this news, the analysis prevented actions that might have wasted important resources for maintaining productive activities in the upper basin, Pohren said. Then, in August 2023, rain began to refill Uruguay’s reservoirs, allowing the country to declare an end to the water crisis.
From right to left: Tiago Pohren, Vanessa Erasun, and Florencia Hastings at the second ISAT workshop in March 2024. Organization of American States Though the immediate water crisis has passed, the tool Pohren created will be useful in the future in Uruguay and around the world. During an ISAT workshop in 2024, he shared his tool with international water resources managers with the hope it could aid their own drought response efforts. And DINAGUA officials still use it to identify and monitor dams, irrigation reservoirs, and other water bodies in Uruguay.
Pohren continues to use NASA training and data to advance reservoir management. He’s currently exploring an ARSET training on how the Surface Water and Ocean Topography (SWOT) mission will further improve the system by allowing DINAGUA to directly measure the height of water in reservoirs. He is also following NASA’s new joint mission with ISRO (the Indian Space Research Organization) called NISAR, which launched on July 30. The NISAR satellite will provide radar data that detects changes in water extent, regardless of cloud cover or time of day. “If a drought happens again,” Pohren said, “with the tools that we have now, we will be much more prepared to understand what the conditions of the basin are and then make predictions.”
Environmental engineer Tiago Pohren conducts a field inspection on the Canelón Grande reservoir, the second-largest reservoir serving Montevideo, during the drought. Tiago Pohren By Melody Pederson, Rachel Jiang
The authors would like to thank Noelia Gonzalez, Perry Oddo, Denise Hill, and Delfina Iervolino for interview support as well as Jerry Weigel for connecting with Tiago about the tool’s development.
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Last Updated Sep 10, 2025 Related Terms
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What Would It Take to Say We Found Life?
We call this the podium test. What would it take for you personally to confidently stand up in front of an international audience and make that claim? When you put it in that way, I think for a lot of scientists, the bar is really high.
So of course, there would be obvious things, you know, a very clear signature of technology or a skeleton or something like that. But we think that a lot of the evidence that we might encounter first will be much more subtle. For example, chemical signs of life that have to be detected above a background of abiotic chemistry. And really, what we see might depend a lot on where we look.
On Mars, for example, the long history of exploration there gives us a lot of context for what we might find. But we’re potentially talking about samples that are billions of years old in those cases, and on Earth, those kinds of samples, the evidence of life is often degraded and difficult to detect.
On the ocean worlds of our outer solar system, so places like Jupiter’s moon Europa and Saturn’s moon Enceladus, there’s the tantalizing possibility of extant life, meaning life that’s still alive. But potentially we’re talking about exceedingly small amounts of samples that would have to be analyzed with a relatively limited amount of instrumentation that can be carried from Earth billions of miles away.
And then for exoplanets, these are planets beyond our own solar system. Really, what we’re looking for there are very large magnitude signs of life that can be detectable through a telescope from many light-years away. So changes like the oxygenation of Earth’s atmosphere or changes in surface color.
So any one of those things, if they rose to the suspicion of being evidence of life, would be really heavily scrutinized in a very sort of specific and custom way to that particular observation. But I think there are also some general principles that we can follow. And the first is just: Are we sure we’re seeing what we think we’re seeing? Many of these environments are not very well known to us, and so we need to convince ourselves that we’re actually seeing a clear signal that represents what we think it represents.
Carl Sagan once said, “Life is the hypothesis of last resort,” meaning that we ought to work hard for such a claim to rule out alternative possibilities. So what are those possibilities? One is contamination. The spacecraft and the instruments that we use to look for evidence of life are built in an environment, Earth, that is full of life. And so we need to convince ourselves that what we’re seeing is not evidence of our own life, but evidence of indigenous life.
If that’s the case, we should ask, should life of the type we’re seeing live there? And finally, we need to ask, is there any other way than life to make that thing, any of the possible abiotic processes that we know and even the ones that we don’t know? And as you can imagine, that will be quite a challenge.
Once we have a piece of evidence in hand that we really do think represents evidence of life, now we can begin to develop hypotheses. For example, do we have separate independent lines of evidence that corroborate what we’ve seen and increase our confidence of life?
Ultimately, all of this has to be looked at hard by the entire scientific community, and in that sense, I think the really operative word in our question is we. What does it take to say we found evidence of life? Because really, the answer, I think, depends on the full scientific community scrutinizing and skepticizing this observation to finally say that we scientists, we as a community and we as humanity found life.
[END VIDEO TRANSCRIPT]
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Scientists believe giant impacts — like the one depicted in this artist’s concept — occurred on Mars 4.5 billion years ago, injecting debris from the impact deep into the planet’s mantle. NASA’s InSight lander detected this debris before the mission’s end in 2022.NASA/JPL-Caltech Rocky material that impacted Mars lies scattered in giant lumps throughout the planet’s mantle, offering clues about Mars’ interior and its ancient past.
What appear to be fragments from the aftermath of massive impacts on Mars that occurred 4.5 billion years ago have been detected deep below the planet’s surface. The discovery was made thanks to NASA’s now-retired InSight lander, which recorded the findings before the mission’s end in 2022. The ancient impacts released enough energy to melt continent-size swaths of the early crust and mantle into vast magma oceans, simultaneously injecting the impactor fragments and Martian debris deep into the planet’s interior.
There’s no way to tell exactly what struck Mars: The early solar system was filled with a range of different rocky objects that could have done so, including some so large they were effectively protoplanets. The remains of these impacts still exist in the form of lumps that are as large as 2.5 miles (4 kilometers) across and scattered throughout the Martian mantle. They offer a record preserved only on worlds like Mars, whose lack of tectonic plates has kept its interior from being churned up the way Earth’s is through a process known as convection.
A cutaway view of Mars in this artist’s concept (not to scale) reveals debris from ancient impacts scattered through the planet’s mantle. On the surface at left, a meteoroid impact sends seismic signals through the interior; at right is NASA’s InSight lander.NASA/JPL-Caltech The finding was reported Thursday, Aug. 28, in a study published by the journal Science.
“We’ve never seen the inside of a planet in such fine detail and clarity before,” said the paper’s lead author, Constantinos Charalambous of Imperial College London. “What we’re seeing is a mantle studded with ancient fragments. Their survival to this day tells us Mars’ mantle has evolved sluggishly over billions of years. On Earth, features like these may well have been largely erased.”
InSight, which was managed by NASA’s Jet Propulsion Laboratory in Southern California, placed the first seismometer on Mars’ surface in 2018. The extremely sensitive instrument recorded 1,319 marsquakes before the lander’s end of mission in 2022.
NASA’s InSight took this selfie in 2019 using a camera on its robotic arm. The lander also used its arm to deploy the mission’s seismometer, whose data was used in a 2025 study showing impacts left chunks of debris deep in the planet’s interior.NASA/JPL-Caltech Quakes produce seismic waves that change as they pass through different kinds of material, providing scientists a way to study the interior of a planetary body. To date, the InSight team has measured the size, depth, and composition of Mars’ crust, mantle, and core. This latest discovery regarding the mantle’s composition suggests how much is still waiting to be discovered within InSight’s data.
“We knew Mars was a time capsule bearing records of its early formation, but we didn’t anticipate just how clearly we’d be able to see with InSight,” said Tom Pike of Imperial College London, coauthor of the paper.
Quake hunting
Mars lacks the tectonic plates that produce the temblors many people in seismically active areas are familiar with. But there are two other types of quakes on Earth that also occur on Mars: those caused by rocks cracking under heat and pressure, and those caused by meteoroid impacts.
Of the two types, meteoroid impacts on Mars produce high-frequency seismic waves that travel from the crust deep into the planet’s mantle, according to a paper published earlier this year in Geophysical Research Letters. Located beneath the planet’s crust, the Martian mantle can be as much as 960 miles (1,550 kilometers) thick and is made of solid rock that can reach temperatures as high as 2,732 degrees Fahrenheit (1,500 degrees Celsius).
Scrambled signals
The new Science paper identifies eight marsquakes whose seismic waves contained strong, high-frequency energy that reached deep into the mantle, where their seismic waves were distinctly altered.
“When we first saw this in our quake data, we thought the slowdowns were happening in the Martian crust,” Pike said. “But then we noticed that the farther seismic waves travel through the mantle, the more these high-frequency signals were being delayed.”
Using planetwide computer simulations, the team saw that the slowing down and scrambling happened only when the signals passed through small, localized regions within the mantle. They also determined that these regions appear to be lumps of material with a different composition than the surrounding mantle.
With one riddle solved, the team focused on another: how those lumps got there.
Turning back the clock, they concluded that the lumps likely arrived as giant asteroids or other rocky material that struck Mars during the early solar system, generating those oceans of magma as they drove deep into the mantle, bringing with them fragments of crust and mantle.
Charalambous likens the pattern to shattered glass — a few large shards with many smaller fragments. The pattern is consistent with a large release of energy that scattered many fragments of material throughout the mantle. It also fits well with current thinking that in the early solar system, asteroids and other planetary bodies regularly bombarded the young planets.
On Earth, the crust and uppermost mantle is continuously recycled by plate tectonics pushing a plate’s edge into the hot interior, where, through convection, hotter, less-dense material rises and cooler, denser material sinks. Mars, by contrast, lacks tectonic plates, and its interior circulates far more sluggishly. The fact that such fine structures are still visible today, Charalambous said, “tells us Mars hasn’t undergone the vigorous churning that would have smoothed out these lumps.”
And in that way, Mars could point to what may be lurking beneath the surface of other rocky planets that lack plate tectonics, including Venus and Mercury.
More about InSight
JPL managed InSight for NASA’s Science Mission Directorate. InSight was part of NASA’s Discovery Program, managed by the agency’s Marshall Space Flight Center in Huntsville, Alabama. Lockheed Martin Space in Denver built the InSight spacecraft, including its cruise stage and lander, and supported spacecraft operations for the mission.
A number of European partners, including France’s Centre National d’Études Spatiales (CNES) and the German Aerospace Center (DLR), supported the InSight mission. CNES provided the Seismic Experiment for Interior Structure (SEIS) instrument to NASA, with the principal investigator at IPGP (Institut de Physique du Globe de Paris). Significant contributions for SEIS came from IPGP; the Max Planck Institute for Solar System Research (MPS) in Germany; the Swiss Federal Institute of Technology (ETH Zurich) in Switzerland; Imperial College London and Oxford University in the United Kingdom; and JPL. DLR provided the Heat Flow and Physical Properties Package (HP3) instrument, with significant contributions from the Space Research Center (CBK) of the Polish Academy of Sciences and Astronika in Poland. Spain’s Centro de Astrobiología (CAB) supplied the temperature and wind sensors.
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Last Updated Aug 28, 2025 Related Terms
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