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By NASA
4 min read
NASA Satellites Reveal Abrupt Drop in Global Freshwater Levels
Earth (ESD) Earth Home Explore Climate Change Science in Action Multimedia Data For Researchers GRACE satellites measure gravity as they orbit the planet to reveal shifting levels of water on the Earth (artist’s concept). NASA/JPL-Caltech An international team of scientists using observations from NASA-German satellites found evidence that Earth’s total amount of freshwater dropped abruptly starting in May 2014 and has remained low ever since. Reporting in Surveys in Geophysics, the researchers suggested the shift could indicate Earth’s continents have entered a persistently drier phase.
From 2015 through 2023, satellite measurements showed that the average amount of freshwater stored on land — that includes liquid surface water like lakes and rivers, plus water in aquifers underground — was 290 cubic miles (1,200 cubic km) lower than the average levels from 2002 through 2014, said Matthew Rodell, one of the study authors and a hydrologist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “That’s two and a half times the volume of Lake Erie lost.”
During times of drought, along with the modern expansion of irrigated agriculture, farms and cities must rely more heavily on groundwater, which can lead to a cycle of declining underground water supplies: freshwater supplies become depleted, rain and snow fail to replenish them, and more groundwater is pumped. The reduction in available water puts a strain on farmers and communities, potentially leading to famine, conflicts, poverty, and an increased risk of disease when people turn to contaminated water sources, according to a UN report on water stress published in 2024.
The team of researchers identified this abrupt, global decrease in freshwater using observations from the Gravity Recovery and Climate Experiment (GRACE) satellites, operated by the German Aerospace Center, German Research Centre for Geosciences, and NASA. GRACE satellites measure fluctuations in Earth’s gravity on monthly scales that reveal changes in the mass of water on and under the ground. The original GRACE satellites flew from March 2002 to October 2017. The successor GRACE–Follow On (GRACE–FO) satellites launched in May 2018.
This map shows the years that terrestrial water storage hit a 22-year minimum (i.e., the land was driest) at each location, based on data from the GRACE and GRACE/FO satellites. A significantly large portion of the global land surface reached this minimum in the nine years since 2015, which happen to be the nine warmest years in the modern temperature record. Image by NASA Earth Observatory/Wanmei Liang with data courtesy of Mary Michael O’Neill The decline in global freshwater reported in the study began with a massive drought in northern and central Brazil, and was followed shortly by a series of major droughts in Australasia, South America, North America, Europe, and Africa. Warmer ocean temperatures in the tropical Pacific from late 2014 into 2016, culminating in one of the most significant El Niño events since 1950, led to shifts in atmospheric jet streams that altered weather and rainfall patterns around the world. However, even after El Niño subsided, global freshwater failed to rebound. In fact, Rodell and team report that 13 of the world’s 30 most intense droughts observed by GRACE occurred since January 2015. Rodell and colleagues suspect that global warming might be contributing to the enduring freshwater depletion.
Global warming leads the atmosphere to hold more water vapor, which results in more extreme precipitation, said NASA Goddard meteorologist Michael Bosilovich. While total annual rain and snowfall levels may not change dramatically, long periods between intense precipitation events allow the soil to dry and become more compact. That decreases the amount of water the ground can absorb when it does rain.
“The problem when you have extreme precipitation,” Bosilovich said, “is the water ends up running off,” instead of soaking in and replenishing groundwater stores. Globally, freshwater levels have stayed consistently low since the 2014-2016 El Niño, while more water remains trapped in the atmosphere as water vapor. “Warming temperatures increase both the evaporation of water from the surface to the atmosphere, and the water-holding capacity of the atmosphere, increasing the frequency and intensity of drought conditions,” he noted.
While there are reasons to suspect that the abrupt drop in freshwater is largely due to global warming, it can be difficult to definitively link the two, said Susanna Werth, a hydrologist and remote sensing scientist at Virginia Tech, who was not affiliated with the study. “There are uncertainties in climate predictions,” Werth said. “Measurements and models always come with errors.”
It remains to be seen whether global freshwater will rebound to pre-2015 values, hold steady, or resume its decline. Considering that the nine warmest years in the modern temperature record coincided with the abrupt freshwater decline, Rodell said, “We don’t think this is a coincidence, and it could be a harbinger of what’s to come.”
By James R. Riordon
NASA’s Earth Science News Team
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Last Updated Nov 15, 2024 Editor James Riordon Contact James Riordon james.r.riordon@nasa.gov Location NASA Goddard Space Flight Center Related Terms
Earth Goddard Space Flight Center GRACE (Gravity Recovery And Climate Experiment) GRACE-FO (Gravity Recovery and Climate Experiment Follow-on) Water on Earth Explore More
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By NASA
4 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater)
Note: The following article is part of a series highlighting propulsion testing at NASA’s Stennis Space Center. To access the entire series, please visit: https://www.nasa.gov/feature/propulsion-powering-space-dreams/.
Crews at NASA’s Stennis Space Center work Jan. 21-22, 2020, to install the first flight core stage of NASA’s powerful SLS (Space Launch System) rocket on the B-2 side of the Thad Cochran Test Stand for a Green Run test series. Operations required crews to lift the massive core stage from a horizontal position into a vertical orientation, a procedure known as “break over.” Once the stage was oriented in a horizontal position on the night of Jan. 21, crews tied it in place to await favorable wind conditions. The following morning, crews began the process of raising, positioning, and securing the stage on the stand. NASA/Stennis The future is now at NASA’s Stennis Space Center near Bay St. Louis, Mississippi – at least when it comes to helping power the next great era of human space exploration.
NASA Stennis is contributing directly to the agency’s effort to land the first woman, the first person of color, and its first international partner astronaut on the Moon – for the benefit of all humanity. Work at the nation’s largest – and premier – propulsion test site will help power SLS (Space Launch System) rockets on future Artemis missions to enable long-term lunar exploration and prepare for the next giant leap of sending the first astronauts to Mars.
“We play a critical role to ensure the safety of astronauts on future Artemis missions,” NASA Stennis Space Center Director John Bailey said. “Our dedicated workforce is excited and proud to be part of NASA’s return to the Moon.”
NASA Stennis achieved an RS-25 testing milestone in April at the Fred Haise Test Stand. Completion of the successful RS-25 certification series provided critical data for L3Harris (formerly known as Aerojet Rocketdyne) to produce new RS-25 engines, using modern processes and manufacturing techniques. The engines will help power SLS rockets beginning with Artemis V.
The first four Artemis missions are using modified space shuttle main engines also tested at NASA Stennis. For each Artemis mission, four RS-25 engines, along with a pair of solid rocket boosters, power the SLS rocket to produce more than 8.8 million pounds of total combined thrust at liftoff.
NASA’s powerful SLS rocket is the only rocket that can send the Orion spacecraft, astronauts, and cargo to the Moon on a single mission.
Following key test infrastructure upgrades near the Fred Haise Test Stand, NASA Stennis will be ready for more RS-25 engine testing. NASA has awarded L3Harris contracts to provide 24 new engines, supporting SLS launches for Artemis V through Artemis IX.
“Every RS-25 engine that launches Artemis to space will be tested at NASA Stennis,” said Joe Schuyler, director of the NASA Stennis Engineering and Test Directorate. “We take pride in helping to power this nation’s human space exploration program. We also take great care in testing these engines because they are launching astronauts to space. We always have safety in mind.”
NASA’s Stennis Space Center conducts a successful hot fire of the first flight core stage of NASA’s powerful SLS (Space Launch System) rocket on the B-2 side of the Thad Cochran Test Stand on March 18, 2021. NASA employees, as well as NASA astronauts Jessica Meir and Zena Cardman, watched the milestone moment. The hot fire of more than eight minutes marked the culmination of a Green Run series of tests on the stage and its integrated systems. NASA/Stennis In addition to RS-25 testing, preparations are ongoing at the Thad Cochran Test Stand (B-2) for future testing of the agency’s new exploration upper stage. The more powerful SLS second stage, which will send astronauts and cargo to deep space aboard the Orion spacecraft, is being built at NASA’s Michoud Assembly Facility in New Orleans.
Before its first flight, the NASA Stennis test team will conduct a series of Green Run tests on the new stage’s integrated systems to demonstrate it is ready to fly. Crews completed installation of a key component for testing the upper stage in October. The lift and installation of the 103-ton interstage simulator component, measuring 31 feet in diameter and 33 feet tall, provided crews best practices for moving and handling the actual flight hardware when it arrives to NASA Stennis.
The exploration upper stage Green Run test series will culminate with a hot fire of the stage’s four RL10 engines, made by L3Harris, the lead SLS engines contractor.
“All of Mississippi shares in our return to the Moon with the next great era of human space exploration going through NASA Stennis,” Bailey said. “Together, we can be proud of the state’s contributions to NASA’s great mission.”
For information about NASA’s Stennis Space Center, visit:
Stennis Space Center – NASA
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Last Updated Nov 13, 2024 EditorNASA Stennis CommunicationsContactC. Lacy Thompsoncalvin.l.thompson@nasa.gov / (228) 688-3333LocationStennis Space Center Related Terms
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By European Space Agency
Torrential rainfall causing deadly flash floods has hit southern and eastern Spain in regions including the Costa del Sol, where the city of Malaga is located, and Valencia in the east. As these areas struggle to cope with the aftermath, satellite technology has played a crucial role in assessing the damages of the affected areas.
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By European Space Agency
At the International Astronautical Congress (IAC) in Milan this week, ESA signed a contract for Element #1, the first phase of the HydRON Demonstration System. HydRON, which stands for High thRoughput Optical Network, is set to transform the way data-collecting satellites communicate, using laser technology that will allow satellites to connect with each other and ground networks much faster.
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By European Space Agency
This week, at the International Aeronautics Congress in Milan, ESA officially kicked off a new project called Ciseres, a small satellite mission designed to significantly improve crisis response times using artificial intelligence (AI). Part of ESA's Civil Security from Space (CSS) programme, Ciseres aims to enhance satellite capabilities to alert first responders and government officials within minutes of the occurrence of a disaster – such as floods, fires, landslides. The project is led and co-financed by Deimos, a European space tech company specialising in small satellite missions.
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