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By European Space Agency
Today, the European Space Agency signed six contracts that will help position Greece as a key player in the field of Earth observation.
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By NASA
4 min read
NASA’s Swift Studies Gas-Churning Monster Black Holes
A pair of monster black holes swirl in a cloud of gas in this artist’s concept of AT 2021hdr, a recurring outburst studied by NASA’s Neil Gehrels Swift Observatory and the Zwicky Transient Facility at Palomar Observatory in California. NASA/Aurore Simonnet (Sonoma State University) Scientists using observations from NASA’s Neil Gehrels Swift Observatory have discovered, for the first time, the signal from a pair of monster black holes disrupting a cloud of gas in the center of a galaxy.
“It’s a very weird event, called AT 2021hdr, that keeps recurring every few months,” said Lorena Hernández-García, an astrophysicist at the Millennium Institute of Astrophysics, the Millennium Nucleus on Transversal Research and Technology to Explore Supermassive Black Holes, and University of Valparaíso in Chile. “We think that a gas cloud engulfed the black holes. As they orbit each other, the black holes interact with the cloud, perturbing and consuming its gas. This produces an oscillating pattern in the light from the system.”
A paper about AT 2021hdr, led by Hernández-García, was published Nov. 13 in the journal Astronomy and Astrophysics.
The dual black holes are in the center of a galaxy called 2MASX J21240027+3409114, located 1 billion light-years away in the northern constellation Cygnus. The pair are about 16 billion miles (26 billion kilometers) apart, close enough that light only takes a day to travel between them. Together they contain 40 million times the Sun’s mass.
Scientists estimate the black holes complete an orbit every 130 days and will collide and merge in approximately 70,000 years.
AT 2021hdr was first spotted in March 2021 by the Caltech-led ZTF (Zwicky Transient Facility) at the Palomar Observatory in California. It was flagged as a potentially interesting source by ALeRCE (Automatic Learning for the Rapid Classification of Events). This multidisciplinary team combines artificial intelligence tools with human expertise to report events in the night sky to the astronomical community using the mountains of data collected by survey programs like ZTF.
“Although this flare was originally thought to be a supernova, outbursts in 2022 made us think of other explanations,” said co-author Alejandra Muñoz-Arancibia, an ALeRCE team member and astrophysicist at the Millennium Institute of Astrophysics and the Center for Mathematical Modeling at the University of Chile. “Each subsequent event has helped us refine our model of what’s going on in the system.”
Since the first flare, ZTF has detected outbursts from AT 2021hdr every 60 to 90 days.
Hernández-García and her team have been observing the source with Swift since November 2022. Swift helped them determine that the binary produces oscillations in ultraviolet and X-ray light on the same time scales as ZTF sees them in the visible range.
The researchers conducted a Goldilocks-type elimination of different models to explain what they saw in the data.
Initially, they thought the signal could be the byproduct of normal activity in the galactic center. Then they considered whether a tidal disruption event — the destruction of a star that wandered too close to one of the black holes — could be the cause.
Finally, they settled on another possibility, the tidal disruption of a gas cloud, one that was bigger than the binary itself. When the cloud encountered the black holes, gravity ripped it apart, forming filaments around the pair, and friction started to heat it. The gas got particularly dense and hot close to the black holes. As the binary orbits, the complex interplay of forces ejects some of the gas from the system on each rotation. These interactions produce the fluctuating light Swift and ZTF observe.
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Watch as a gas cloud encounters two supermassive black holes in this simulation. The complex interplay of gravitational and frictional forces causes the cloud to condense and heat. Some of the gas is ejected from the system with each orbit of the black holes. F. Goicovic et al. 2016 Hernández-García and her team plan to continue observations of AT 2021hdr to better understand the system and improve their models. They’re also interested in studying its home galaxy, which is currently merging with another one nearby — an event first reported in their paper.
“As Swift approaches its 20th anniversary, it’s incredible to see all the new science it’s still helping the community accomplish,” said S. Bradley Cenko, Swift’s principal investigator at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “There’s still so much it has left to teach us about our ever-changing cosmos.”
NASA’s missions are part of a growing, worldwide network watching for changes in the sky to solve mysteries of how the universe works.
Goddard manages the Swift mission in collaboration with Penn State, the Los Alamos National Laboratory in New Mexico, and Northrop Grumman Space Systems in Dulles, Virginia. Other partners include the University of Leicester and Mullard Space Science Laboratory in the United Kingdom, Brera Observatory in Italy, and the Italian Space Agency.
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By Jeanette Kazmierczak
NASA’s Goddard Space Flight Center, Greenbelt, Md.
Media Contact:
Claire Andreoli
301-286-1940
claire.andreoli@nasa.gov
NASA’s Goddard Space Flight Center, Greenbelt, Md.
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Last Updated Nov 13, 2024 Editor Jeanette Kazmierczak Related Terms
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By NASA
5 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/.
Contrary to the popular saying, work conducted by the propulsion test team at NASA’s Stennis Space Center is rocket science – and requires all the talent, knowledge, and expertise the term implies.
Rocket science at NASA Stennis, located near Bay St. Louis, Mississippi, has helped safely power American space dreams for almost 60 years ago. The accumulated knowledge and skills of the site’s test team continue to benefit NASA and commercial aerospace companies, thanks to new generations of skilled engineers and operators.
“The innovative, can-do attitude started with the founding of the south Mississippi site more than six decades ago,” said NASA Stennis Director John Bailey. “The knowledge, skills, and insight of a versatile team continue supporting NASA’s mission and goals of commercial aerospace companies by routinely conducting successful propulsion testing at NASA Stennis.”
Test team personnel perform facility data review following completion of a liquid oxygen cold-flow activation activity on the E-1 Test Stand at NASA’s Stennis Space Center on March 23, 2016. Activation of the test cell was in preparation for testing L3Harris’ (then known as Aerojet Rocketdyne) AR1 rocket engine pre-burner and main injector. The versatile four-stand E Test Complex includes 12 active test cell positions capable of various component, engine, and stage test activities for NASA and commercial projects. NASA/Stennis Operators at NASA’s High Pressure Gas Facility conduct a critical stress test Oct. 18-19, 2018, to demonstrate the facility’s readiness to support testing of the core stage of NASA’s powerful SLS (Space Launch System) rocket. The High Pressure Gas Facility was critical in producing and delivering gases needed for SLS core stage testing ahead of the successful launch of Artemis I. NASA/Stennis Test control center crews at NASA’s Stennis Space Center’s simulate full operations of core stage testing Dec. 13, 2019, for NASA’s powerful SLS (Space Launch System) rocket on the Thad Cochran Test Stand (B-2). NASA Stennis conducted SLS core stage testing in 2020-21 ahead of the successful Artemis I mission. NASA/Stennis A sitewide stress test at NASA’s Stennis Space Center on Dec. 13, 2019, simulates full operations needed during SLS (Space Launch System) core stage testing. The 24-hour exercise involved crews across NASA Stennis, including at the High Pressure Water Facility that provided needed generator power and water flow to the Thad Cochran Test Stand (B-2) during testing.NASA/Stennis The NASA Stennis team exhibits a depth and breadth of experience and expertise likely unsurpassed anywhere in the world.
The depth is built on decades of propulsion test experience. Veteran team members of today learned from those working during the Apollo era, who overcame various engineering, technical, communications, and mechanical difficulties in testing the Saturn V rocket stages that powered humans to the Moon. During 43 stage firings, the team accumulated an estimated 2,475 years of rocket engine test expertise.
Members of the Apollo test team then joined with new engineers and operators to test main engines that powered 30 years of space shuttle missions. From 1975 to 2009, the team supported main engine development, certification, acceptance, and anomaly testing with over 2,300 hot fires and more than 820,000 seconds of accumulated hot-fire time.
“NASA Stennis is unique because of the proven test operations expertise passed from generation to generation,” said Joe Schuyler, director of the NASA Stennis Engineering and Test Directorate. “It is expertise you can trust to deliver what is needed.”
A member of the Fred Haise Test Stand (formerly the A-1 Test Stand) operations team examines the progress of a cold-shock test on May 1, 2014. The test marked a milestone in preparing the stand to test RS-25 rocket engines that will help power NASA’s SLS (Space Launch System) rocket.NASA/Stennis In addition to depth, the site team also has a breadth of experience that gives it unparalleled versatility and adaptability.
Part of that comes from the nature of the center itself. NASA Stennis is the second largest NASA center in terms of geography, but the civil servant workforce is small. As a result, test team members work on a range of propulsion projects, from testing components on smaller E Test Complex cells to firing large engines and even rocket stages on the heritage Apollo-era stands.
“Our management have put us in a position to be successful,” said NASA engineer Josh Greiner. “They have helped move us onto the test stands and given us a huge share of the responsibility of leading projects early in our career, which provides us the confidence and opportunity to conduct tests.”
In addition, center leaders made a deliberate decision more than a decade ago to return test stand operations to the NASA team. Prior to that time, stand operations were in the hands of contractors under NASA supervision. The shift allowed the civil servant test team to fine-tune its skill set even as it continued to work closely with contractor partners to support both government and commercial aerospace propulsion projects.
An image from October 2022 shows NASA engineers preparing for the next RS-25 engine test series at NASA’s Stennis Space Center by monitoring the reload of propellant tanks to the Fred Haise Test Stand (formerly the A-1 Test Stand). RS-25 engines are powered by a mix of liquid hydrogen and liquid oxygen.NASA/Stennis An image from October 2022 shows test team personnel ensuring pressures and flow paths are set properly for liquid oxygen to be transferred to the Fred Haise Test Stand (formerly the A-1 Test Stand), pictured in the background.NASA/Stennis An image from August 2023 shows test team personnel inspecting a pump during an initial chill down activity at the E-3 Test Complex. The versatile four-stand E Test Complex includes 12 active test cell positions capable of various component, engine, and stage test activities for NASA and commercial programs and projects. NASA/Stennis An image from September 2023 shows test team personnel preparing for future SLS (Space Launch System) exploration upper stage testing that will take place on the B-2 side of the Thad Cochran Test Stand. NASA’s new upper stage is being built as a more powerful SLS second stage to send the Orion spacecraft and heavier payloads to deep space. It will fly on the Artemis missions following a series of Green Run tests of its integrated systems at NASA Stennis. The test series will culminate with a hot fire of the four RL10 engines that will power the upper stage.NASA/Stennis An image from September 2023 shows test team personnel preparing for future SLS (Space Launch System) exploration upper stage testing by conducting a liquid hydrogen flow procedure. NASA’s new upper stage is being built as a more powerful SLS second stage to send the Orion spacecraft and heavier payloads to deep space. The upper stage will undergo a series of Green Run tests of its integrated systems on the B-2 side of the Thad Cochran Test Stand at NASA Stennis.NASA/Stennis The evolution and performance of the NASA Stennis team was illustrated in stark fashion in June/July 2018 when a blended team of NASA, Defense Advanced Research Projects Agency, Aerojet Rocketdyne, Boeing, and Syncom Space Services engineers and operators test fired an AR-22 rocket engine 10 times in a 240-hour period.
The campaign marked the first time a large liquid oxygen/liquid hydrogen engine had been tested so often in such a short period of time. The test team overcame a variety of challenges, including a pair of lightning strikes that threatened to derail the entire effort. Following completion of the historic series, a NASA engineer who helped lead the campaign recounted one industry observer who repeatedly characterized the site’s test team as nothing less than a national asset.
The experienced site workforce now tests RS-25 engines and propulsion systems for NASA’s Artemis campaign, including those that will help power Artemis missions to the Moon for scientific discovery and economic benefits. The NASA Stennis team also supports a range of commercial aerospace propulsion test activities, facilitating continued growth in capabilities. For instance, the team now has experience working with oxygen, hydrogen, methane, and kerosene propellants.
“The NASA and contractor workforce at NASA Stennis is second to none when it comes to propulsion testing,” Schuyler said. “Many of the current employees have been involved in rocket engine testing for over 30 years, and newer workers are being trained under these seasoned professionals.”
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 NASA
Earth Observer Earth Home Earth Observer Home Editor’s Corner Feature Articles Meeting Summaries News Science in the News Calendars In Memoriam More Archives 22 min read
NASA’s BlueFlux Campaign Supports Blue Carbon Management in South Florida
Photo 1. A Mangrove stand lines the bank of Shark River, an Everglades distributary that carries water into the Gulf of Mexico’s Ponce De Leon Bay. Photo credit: Nathan Marder/NASA’s Goddard Space Flight Center (GSFC) Introduction
Along the southernmost rim of the Florida Peninsula, the arching prop roots or “knees” of red mangroves (Rhizophora mangle) line the coast – see Photo 1. Where they dip below the water’s surface, fish lay their eggs, enjoying the protection from predators that the trees provide. Among their branches, wading birds, such as the great blue heron and the roseate spoonbill establish rookeries to rear their young. The tangled matrix of roots collects organic matter and ocean-bound sediments, adding little-by-little to the coastline and shielding inland biology from the erosive force of the sea. In these ways, mangroves are equal parts products and engineers of their environment, but their ecological value extends far beyond this local sphere of influence.
Mangroves are an important carbon dioxide (CO2) sink – responsible for removing CO2 from the atmosphere with impressive efficiency. Current estimates suggest mangroves sequester CO2 10 times faster and store up to 5 times more carbon than rainforests and old-growth forests. But as part of the ever-changing line between land and sea, they’re exceptionally vulnerable to climate disturbances such as sea level rise, hurricanes, and changes in ocean salinity. As these threats intensify, Florida’s sub-tropical wetlands – and their role as a critical sink of CO2 – face an uncertain future.
NASA’s BlueFlux Campaign, a three-year (2021–2024), $1.5-million project operating under the agency’s Carbon Monitoring System, used field, aircraft, and satellite data to study the impact of both natural and anthropogenic pressures on South Florida’s coastal ecology. BlueFlux consists of a series of ground-based and airborne fieldwork campaigns, providing a framework for the development of a satellite-based data product that will estimate daily rates of surface-atmosphere gas transfer or gaseous flux across coastal ecosystems in Florida and the Caribbean. “The goal is to enhance our understanding of how blue-carbon ecosystems fit into the global carbon market,” said Ben Poulter [NASA’s Goddard Space Flight Center (GSFC)—Project Lead]. “BlueFlux will ultimately answer scientific questions and provide policy-related solutions on the role that coastal wetlands play in reducing atmospheric greenhouse gas (GHG) concentrations.”
This article provides an overview of BlueFlux fieldwork operations – see Figure 1 – and outlines how the project might help refine global GHG budgets and support the restoration of Florida’s wetland ecology.
Figure 1. A map of South Florida overlaying a true-color image captured by the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument on board NASA’s Terra satellite. Red triangles mark locations of primary ground-based fieldwork operations described in this article. Figure Credit: NASA’s Goddard Space Flight Center (GSFC) BlueFlux Ground-based Fieldwork
Across the street from the Flamingo Visitors center, at the base of the Everglades National Park, there was once a thriving mangrove population. Now, the skeletal remains of the trees form one of the Everglades’ largest ghost forests – see Photo 2. When Hurricane Irma made landfall in September 2017, violent winds battered the shore and a storm surge swept across the coast, decimating large swaths of the mangrove forest. Most of Florida’s mangroves recovered swiftly. But seven years later, this site and others like it have seen little to no growth.
“At this point, I doubt they’ll ever recover,” said David Lagomasino [East Carolina University].
Photo 2. A mangrove ghost forest is all that remains of a once-thriving mangrove stand, preserving an image of Hurricane Irma’s lasting impact on South Florida’s wetland ecology. Most of the ghost forests in the region are a product of natural depressions in the landscape that collect saltwater following severe storms. Photo credit: Nathan Marder/NASA’s Goddard Space Flight Center (GSFC) Lagomasino was in the Everglades this summer conducting research as part of the fifth leg of BlueFlux fieldwork – see Photo 3. His team focused on measuring how changes in wetland ecology affect the sequestration and emission rates of both CO2 and methane (CH4). In areas where vegetative health is severely degraded, like in ghost forests, a general decline in CO2 uptake is accompanied by an increase in CH4 production, the net effect of which could dramatically amplify the atmosphere’s ability to trap heat. Ghost forests offer an example at one end of an extreme, but defining the way more subtle gradients among wetland variables – such as changes in water level, tree height, canopy coverage, ocean salinity, or mangrove species distribution – might influence flux is harder to tease out of the limited data available.
Photo 3. Assistant professor David Lagomasino and Ph.D. candidate Daystar Babanawo [both from East Carolina University] explore the lower Everglades by boat. Due to the relative inaccessibility of the region, measurements of flux in wetland ecosystems are limited. The plant life here consists almost entirely of Florida’s three Mangrove species (red, black, and white), which are among the only vegetation that can withstand the brackish waters characteristic of coastal wetlands. Photo credit: Nathan Marder/NASA’s Goddard Space Flight Center (GSFC) In the Everglades, flux measurements are confined to a handful of eddy covariance towers – or flux towers – constructed as part of the National Science Foundation’s (NSF) Long-Term Ecological Research (LTER) Network.
The first flux tower in this network, erected in June 2003, stands near the edge of Shark River at a research site called SRS-6, short for Shark River Slough site 6. A short walk from the riverbank, across a snaking path of rain-weathered, wooden planks, sits a small platform where the flux tower is anchored to the forest floor – see Photo 4. About 20 m (65 feet) above the platform, the tower breaches the canopy, where a suite of instruments continuously measures wind velocity, temperature, humidity, and the vertical movement of trace atmospheric gases, such as water vapor (H2Ov), CO2, and CH4. It’s these measurements collectively that are used to calculate flux.
Photo 4. At SRS-6, an eddy covariance tower measures C02 and CH4 flux among a dense grove of red, black, and white mangroves. The term eddy covariance refers to the statistical technique used to calculate gaseous flux based on the meteorological and scalar atmospheric data collected by the flux towers. Photo credit: Nathan Marder/NASA’s Goddard Space Flight Center (GSFC) “Hundreds of research papers have come from this site,” said Lagomasino. The abundance of research generated from the data captured at SRS-6 speaks in part to the value of the measurements that the tower makes. It also points to the gaps that exist just beyond each tower’s reach. A significant goal of the BlueFlux campaign is to explain flux on a scale that isn’t covered by existing data – to fill in the gaps between the towers.
One way to do that is by gathering data by hand.
On Lagomasino’s boat is a broad, black case carrying a tool called a Russian peat auger. The instrument is designed to extract core samples from soft soils – see Photo 5.
Everglades peat, which is made almost entirely of the partially decomposed roots, stems, and leaves of the surrounding mangroves, offers a perfect study subject. Each thin, half-cylinder sample gets sealed and shipped back to the lab, where it will be sliced into flat discs. The discs will be analyzed for their age and carbon content by Lagomasino’s team and partners at Yale University. These cores are like biomass time capsules. In Florida’s mangrove forests, a 1-m (3-ft) core might represent more than 300 years of carbon accumulation. On average, a 1 to 3 mm (0.04 to 0.12 in) layer of matter is added to the forest floor each year, building up over time like sand filling an hourglass.
Photo 5. David Lagomasino holds a Russian peat auger containing a sample of Everglades peat. The primary source of the soil’s elevated carbon content – evident from its coarse, fibrous texture – is the partially decayed plant tissue of the surrounding mangroves. Photo credit: Nathan Marder/NASA’s Goddard Space Flight Center (GSFC) Although coastal wetlands account for less than 2% of the planet’s land-surface area, they house a disproportionate amount of blue carbon – carbon stored in marine and coastal environments. In the Everglades, the source of this immense accumulation of organic material is the quick-growing vegetation – see Photo 6.
When a CO2 molecule finds its way through one of the many small, porous openings on a mangrove leaf – called stomata – its next step is one of creation, where it plays a part in the miraculous transformation of inorganic matter into living tissue. Inside the leaf’s chloroplasts, energy from stored sunlight kickstarts a long chain of chemical reactions that will ultimately divide CO2 into its constituent parts. Oxygen atoms are returned to the atmosphere as the byproduct of photosynthesis, but the carbon stays behind to help build the sugar molecules that will fuel new plant growth. In short, the same carbon that once flowed through the atmosphere defines the molecular structure of all wetland vegetation. When a plant dies or a gust of wind pulls a leaf to the forest floor, this carbon-based matter finds its way into the soil, where it can stay locked in place for thousands of years thanks to a critical wetland ingredient: water.
The inundated, anoxic – an environment deficient or absent of oxygen – peat soils characteristic of wetlands host microbial populations that are uniquely adapted to their environment. In these low- to no-oxygen conditions, the prevailing microbiota consumes organic material slowly, leading to an accumulation of carbon in the soil. As wetland conditions change, the soil’s microbial balance shifts. For example, a decline in water level, which can increase the oxygen-content of the soil, produces conditions favorable to aerobic bacteria. These oxygen-breathing lifeforms consume organic matter far more rapidly than their anaerobic counterparts – and release more CO2 into the atmosphere as a result.
Water level isn’t the only environmental condition that influences rates of carbon sequestration. The soil cores collected during the campaign will be analyzed alongside records of interrelated variables such as water salinity, sea surface height, and temperature to understand not just the timescales associated with blue carbon development in mangrove forests but how and why rates of soil deposition change in response to specific environmental pressures. In many parts of the Everglades, accumulated peat can reach depths of up to 3 m (9.8 feet) – holding thousands of years’ worth of insights that would otherwise be lost to time.
Photo 6. Mangroves are viviparous plants. Their propagules – or seedlings – germinate while still attached to their parent tree. Propagules that fall to the forest floor are primed to begin life as soon as they hit the ground. But even those that fall into bodies of water and are carried out to sea can float for months before finding a suitable place to lay their roots. The high growth rate of mangroves contributes to the efficiency with which mangrove forests remove CO2 from the atmosphere. Photo credit: Nathan Marder/NASA’s Goddard Space Flight Center (GSFC) Lola Fatoyinbo [NASA’s Goddard Space Flight Center (GSFC), Biospheric Sciences Lab] and Peter Raymond [Yale University’s School of the Environment] led additional fieldwork teams tasked with collecting forest inventory data in locations where vegetation was dead, regenerating, or recently disturbed by severe weather events. A terrestrial laser system was used to obtain three-dimensional (3D) images of mangrove forest structure, which provided maps of stem density, vertical distributions of biomass, and stand volume surface area. Spectroradiometers were also used to acquire visible, near infrared, and shortwave infrared spectra, delivering detailed information about species composition, vegetative health, water levels, and soil properties.
To tie these variables to flux, the researchers made measurements using chambers – see Figure 2 – designed to adhere neatly to points where significant rates of gas exchange occur, (i.e., mangrove lenticels—cell-sized breathing pores found on tree bark and root systems— and the forest floor). As an example, black mangroves (Avicennia germinans) possess unique aerial roots called pneumatophores that, similar to the prop roots of red mangroves, provide them with access to atmospheric oxygen. Pneumatophores sprout vertically from the forest floor and line up like matchsticks around the base of each tree. The team used cylindrical chambers to measure the transfer of gas between a single pneumatophore and the atmosphere – see Figure 2a.
These observations are archived in NASA’s Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC) and publicly available to researchers who wish to monitor and identify trends in the data. After nearly three years of field work, these data have already given scientists a more detailed picture of how Florida’s wetlands are responding to environmental pressures.
Research based on data from early BlueFlux fieldwork deployments confirms that aerobic, methanogenic microbes living in flooded, wetland soils naturally release a significant amount of CH4 as a byproduct of the process by which they create their own energy.
“We’re especially interested in this methane part,” said Fatoyinbo. “It’s the least understood, and there’s a lot more of it than we previously thought.” Fatoyinbo also noted a “significant difference in CO2 and CH4 fluxes between healthy mangroves and degraded ones.” In areas where mangrove health is in decline, due to reduced freshwater levels or as the result of damage sustained during severe weather events, “you can end up with more ‘bad’ gases in the atmosphere,” she said. Since CH4 is roughly 80 times more potent than CO2 over 100-year period, these emissions can undermine some of the net benefits that blue carbon ecosystems provide as a sink of atmospheric carbon.
Figure 2. To directly measure the emission and sequestration rates of CO2 and CH4 in mangrove forests, chambers were designed to adhere to specific targets where gas exchange occurs (i.e. mangrove lenticles, root systems, and the forest floor). Credit: GSFC Airborne Research Teams Measure GHG Flux from Above
Florida’s mangrove forests blanket roughly 966 km2 (600 mi2) of coastal terrain. Even with over 20 years of tower data and the extensive measurements from ground-based fieldwork operations, making comprehensive inferences about the entire ecosystem is tenuous work. To provide flux data at scale – and help quantify the atmospheric influence that Florida’s coastal wetlands carry as a whole – NASA’s BlueFlux campaign relies on a relatively new, airborne technique for measuring flux – see Photo 7.
Photo 7. At the Miami Executive Airfield, members of NASA’s BlueFlux airborne science team stand in front of the Beechcraft 200 King Air before the final flight of the fieldwork campaign. Photo credit: Nathan Marder/NASA’s Goddard Space Flight Center (GSFC) Between 2022 and 2024, over 5 deployments, the team conducted more than 34 carefully planned flights – see Figure 3 – collecting flux data over Florida’s wetlands by plane. Each flight is equipped with a payload known colloquially as “CARAFE,” short for the CARbon Airborne Flux Experiment, which is the airborne campaign’s primary means of data collection. “This is one of the first times an instrument like this has flown over a mangrove forest anywhere in the world,” said Fatoyinbo. “So, it’s really just kind of groundbreaking.”
Figure 3. An example of flight paths from eight BlueFlux airborne deployments flown in April 2023. The flight paths are highlighted in blue. The legs of each flight where flux measurements were taken are highlighted in green. Accurate flux calculations rely on stable measurements of the aircraft’s speed and orientation, which is why the flux legs of each flight are flown in straight lines. Credit: GSFC In the air, GHG concentrations are measured using a well-established technique called cavity ringdown spectroscopy, which involves firing a laser into a small cavity where it will ping back and forth between two highly reflective mirrors. Most gas-phase molecules absorb light at specific wavelengths, depending on their atomic makeup. Since the target molecules in this case are CO2 and CH4, the laser is configured to emit light at a wavelength that only these molecules will absorb. As the laser bounces between the mirrors, a fraction of the light is absorbed by any molecules present in the chamber. The rate of the light’s decay is used to estimate CO2 and CH4 concentrations, generating a time series with continuous readings of gas concentrations, measured in parts per million – see Photo 8. This information is combined with measurements of vertical wind velocity to calculate a corresponding time series of fluxes along the flight track. While these measurements are important on their own, a priority for the airborne team is understanding GHG fluxes in relation to what’s happening on the ground.
Photo 8. The CARAFE payload is responsible for taking readings of atmospheric CO2, CH4, and H2Ov levels using a wind probe and two optical spectroscopy instruments manufactured by Picarro: the G2401m Gas Concentration Analyzer and the G2311f Gas Concentration Analyzer. The readings pictured above were made by the G2311f, which measures gas concentrations at a faster rate than the G2401m. The G2401m makes slower but more stable measurements, which are necessary for verifying the accuracy of measurements made by the G2311f. Photo credit: Nathan Marder/NASA’s Goddard Space Flight Center (GSFC) Unlike flux towers, which only collect data within a 100 m2 (328 ft2) “footprint,” airborne readings have a footprint that can stretch up to 1 km (0.6 mi) in upwind directions. The plane’s speed, position, and orientation are used to help link flux data to fixed points along the flight’s path – so the team can make comparisons between aerial measurements and those made by the ground-based towers – see Photo 9.
“One challenge with that is the flux towers are much lower to the ground, and their footprint is much smaller,” said Glenn Wolfe [GSFC—BlueFlux Flight Lead]. “So, we have to be really careful with our airborne observations, to make sure they closely resemble our ground-based measurements.”
Part of decoding the airborne data involves overlaying each footprint with detailed maps of different surface properties, such as vegetation cover, soil water depth, or leaf-area index, so the team can constrain the measurements and assign fluxes to specific sources – whether its mangroves, sawgrass, or even water.
Photo 9. The BlueFlux airborne science team collects flux measurements from 90m (300ft) above Florida’s mangrove forests. Photo credit: Nathan Marder/NASA’s Goddard Space Flight Center (GSFC) Data Upscaling – Making Daily Flux Predictions from Space
The coupling of BlueFlux’s ground-based and airborne data provides the framework for the production of a broader, regional image of GHG flux.
“The eddy flux towers give us information about the temporal variability,” said Cheryl Doughty [GSFC]. “And the airborne campaign gives us this great intermediate dataset that allows us to go from individual trees to a much larger area.”
Doughty is now using BlueFlux data to train a remote-sensing data product, the prototype of which is called Daily Flux Predictions for South Florida. The product’s underlying model relies on machine learning algorithms and an ensemble modeling technique called random forest regression. It will make flux predictions based on surface reflectance data captured by the Moderate Resolution Imaging Spectroradiometer (MODIS), an instrument that flies on NASA’s polar-orbiting Aqua and Terra satellites – see Figure 4.
“We’re really at the mercy of the data that’s out there,” said Doughty. “One of the things we’re trying to produce as part of this project is a daily archive of fluxes, so MODIS is an amazing resource, because it has over 20 years of data at a daily temporal resolution.”
This archival flux data will help researchers explain how fluxes change in relation to processes that are directly described by MODIS surface reflectance data, including sea-level rise, land use, water management, and disturbances from hurricanes and fires.
Figure 4. Sample of methane flux upscaling, in which MODIS surface reflectance retrievals are used to predict CH4 flux for South Florida at a regional scale [bottom row, left]. The model inputs rely on a composite of MODIS Nadir Bidirectional Reflectance Distribution Function (BRDF)-Adjusted Radiance (NBAR) measurements from all available MODIS land bands: [top row, left to right]: red (620–670 nm), green (545–565 nm), blue (459–479 nm); [middle row, left to right] near infrared 1, or NIR1 (841–876 nm), NIR2 (1230–1250 nm), shortwave IR 1, or SWIR1 (1628–1652 nm), and SWIR 2 (2105–2155 nm). The Everglades National Park boundary is indicated on each image with a white line. Output of the model is shown [bottom row, left] as well as a comparison between modeled fluxes of MODIS NBAR with Terra and Aqua [bottom row, right]. Credit: GSFC To help validate the model, researchers must reformat flux measurements from the airborne campaign to match the daily temporal resolution and 500m2 (0.3mi2) spatial resolution of MODIS reflectance retrievals.
“It’s best practice to meet the data at the coarsest resolution,” said Doughty. “So, we have to take an average of the hourly estimates to match MODIS’ daily scale.”
The matching process is slightly more complicated for spatial datasets. BlueFlux’s airborne flux measurements produce roughly 20 data points for each 500 m2 (0.3 mi2) area, the same resolution as a single MODIS pixel.
“We’re essentially taking an average of all those CARAFE points to get an estimate that corresponds to one pixel,” said Doughty.
This symmetry is critical, allowing the team to test, train, and tune the model using measurements that capture what’s really happening on the ground – ensuring the accuracy of flux measurements generated from satellite data alone.
Researchers don’t expect the model to serve as a perfect reconstruction of reality. The heterogenous nature of Florida’s wetland terrain – which consists of a patchwork of sawgrass marshland, mangrove forests, hardwood hammocks, and freshwater swamps – contributes to high degree of variability in CO2 removal rates within and across its distinct regions. The daily flux product accounts for some of this complexity by making hundreds of calculations at a time, each with slightly different parameters based on in-situ measurements.
“The goal isn’t to just give people one flux measurement but an estimate of the uncertainty that is so inherent to these wetlands,” explained Doughty.
The prototype of the product will be operational by early 2025 and accessible to the public through NASA’s ORNL DAAC. Doughty hopes it will help stakeholders and decision makers evaluate policies related to water management, land use, and conservation that might impact critical stocks of blue carbon.
From Drainage to Restoration in the Florida Everglades
In the late 19th century, land developers were drawn to South Florida, where they hoped the fertile soil and tropical climate could support year-round cultivation of commodities such as exotic fruits, vegetables, and sugar cane. There was just one thing standing in the way – the water. If they could find a way to tame Florida’s wilderness, to drain the wetland of its excess water, Florida would offer Americans a new agricultural frontier.
Progress was made incrementally, but the Everglades drainage project idled for more than 50 years as its organizers wrestled with the literal and political morass surrounding South Florida’s wetland topography. It was mother nature’s hand that ultimately accelerated the drainage project. In 1926 and 1928, two large hurricanes tore through the barrier along Lake Okeechobee’s southern shore built to prevent water from spilling onto the newly settled, small-scale farmland just south of the lake. The second of the two storms – 1928’s Okeechobee Hurricane – made landfall in early September and resulted in nearly 3,000 recorded fatalities. In some areas, the torrent of flood water was deep enough that even those who sought refuge from the flood on the roofs of their homes were swept away by the current. The federal government was forced to step in.
By 1938, the U.S. Army Corps of Engineers had completed construction of the Hoover Dike, adding to a collection of four canals responsible for siphoning water away from Lake Okeechobee’s floodplain and into the Atlantic Ocean. Seasonal flooding was brought under control, but the complete reclamation of South Florida’s wetlands proved more challenging than anticipated. As water levels fell and freshly cleared lands dried out, the high organic content of the soil fueled tremendous peat and muck fires that could burn for days, spreading through underground seams where water once flowed. In some areas, fires consumed the entire topsoil layer – exposing the limestone substrata to the atmosphere for the first time in thousands of years. The engineers in charge of Florida’s early wetland reclamation projects underestimated the value of the state’s hydrological system and overestimated its capacity to withstand human interference.
“Those initial four canals were enough to drain the everglades three times over,” said Fred Sklar [South Florida Water Management District—Everglades System Sciences Director]. “And they still exist, but now there are more than seven million people who rely on them for drinking water and flood control.”
Today, much of the Water Management District’s work involves unwinding the damage wrought by earlier drainage efforts.
“One thing we’re trying to do is make sure these peat fires never happen again,” said Sklar.
But restoring natural water flow to the Everglades – which is critical to the region’s ecological health – isn’t an option. Even if drainage could be reversed, it would subject Florida’s residents to the same flood risks that made drainage a priority. Some residents, including members of the Miccosukee and Seminole tribes, live directly alongside or within Everglades wilderness areas, where the risk of flooding is even greater than it is in the state’s highly populated coastal communities. These areas are also out of reach of the Water Management District’s existing infrastructure. It’s not as simple as turning the tap on and off.
Photo 10. The Tamiami Trail Canal runs across the Florida Peninsula from west to east, towards a saltwater treatment facility near the Miami River. Construction was completed in 1928, shortly after the first four drainage canals opened. It quickly became apparent that the canal and its adjacent roadway dramatically impede water flow to the Everglades wilderness areas to their south, cutting off the region’s vegetation and wildlife from a critical source of freshwater. New modifications to the canal are currently underway, which aim to introduce a hydrological regime that more closely resembles the pre-drainage system. Photo credit: U.S. National Park Service Florida’s Water Management District works with federal agencies, including the U.S. Army Corps of Engineers, to monitor and govern the flow of Florida’s freshwater. The District has overseen the construction and management of dozens of canals, dikes, levees, dredges, and pumps over the last half-century that offer a higher degree of control over Florida’s complex hydrological network – see Photo 10.
“The goal is to restore as much acreage as we can, but we also need to restore it functionally, without degrading the whole system or putting residents at risk,” summarized Sklar. “To do this effectively, we need a detailed understanding of how the hydrology functions and how it influences all of these other systems, such as carbon sequestration.”
Since the 1920s, more than half of Florida’s original wetland coverage has been lost. The present system also carries 65% less peat coverage and 77% less stored carbon than it did prior to drainage. As atmospheric CO2 concentrations climb at unprecedented rates, an accompanying rise in sea levels, severe weather, and ocean salinity all present serious threats to Florida’s wetland ecology – see Figure 5.
“We’re worried about losing that stored carbon,” said Poulter. “But blue carbon also offers tremendous opportunities for climate mitigation if conservation and restoration are properly supported by science.”
Figure 5. A map of the BlueFlux study region, showing mangrove extent (green) and the paths of tropical storms and hurricanes from 2011 to 2021 (red). These storms drive losses in mangrove forest coverage – the result of erosion and wind damage. The inset regions at the top of the image highlight proposed targets for the airborne component of NASA’s BlueFlux Campaign. Figure credit: GSFC Conclusion – The Future of Flux
Every few years, the Intergovernmental Panel on Climate Change (IPCC) releases emissions data and budget reports that have important policy implications related to the Paris Agreement’s goal of limiting global warming to between 1.5°C (2.7°F) and 2°C (3.6°F) compared to pre-industrial levels. Refining the accuracy of global carbon budgets is paramount to reaching that goal, and wetland ecosystems – which have been historically under-represented in climate research – are an important part of the equation.
Early estimates based on BlueFlux fieldwork deployments and upscaled using MODIS surface reflectance data suggest that wetland CH4 emissions in South Florida offset CO2 removal in the region by about 5% based on a 100-year CH4 warming potential, resulting in a net annual CO2 removal of 31.8 Tg (3.18 million metric tons) per year. This is a small fraction of total CO2 emissions in the U.S. and an even smaller fraction of global emissions. In 2023, an estimated 34,800 Tg (34.8 billion metric tons) of CO2 were released into the atmosphere. But relative to their size, the CO2 removal services provided by tropical wetlands are hardly dismissible.
“We’re finding that massive amounts of CO2 are removed and substantial amounts of CH4 are produced, but overall, these ecosystems provide a net climate benefit by removing more greenhouse gases than they produce,” Poulter said.
Access to a daily satellite data product also provides researchers with the means to make more regular adjustments to budgets based on how Florida’s mutable landscape is responding to climate disturbances and restoration efforts in real time.
With the right resources in hand, the scientists who dedicate their careers to understanding and restoring South Florida’s ecology share a hopeful outlook.
“Nature and people can absolutely coexist,” said Meenakshi Chabba [The Everglades Foundation—Ecologist and Resilience Scientist]. “But what we need is good science and good management to reach that goal.”
The Everglades Foundation provides scientific evaluation and guidance to the elected officials and governmental institutions responsible for the implementation of the Comprehensive Everglades Restoration Plan (CERP), a federal program approved by Congress in 2000 that outlines a 30-year plan to restore Florida’s wetland ecology. The Foundation sees NASA’s BlueFlux campaign as an important accompaniment to that goal.
“The [Daily Flux Predictions for South Florida] data product is incredibly valuable, because it provides us with an indicator of the health of the whole system,” said Steve Davis [The Everglades Foundation—Chief Science Officer]. “We know how valuable the wetlands are, but we need this reliable science from NASA and the BlueFlux Campaign to help translate those benefits into something we can use to reach people as well as policymakers.”
Researchers hope the product can inform decisions about the management of Florida’s wetlands, the preservation of which is not only a necessity but – to many – a responsibility.
“These impacts are of our own doing,” added Chabba. “So, now it’s incumbent upon us to make these changes and correct the mistakes of the past.”
Next, the BlueFlux team is shifting their focus to what they call BlueFlux 2. This stage of the project centers around further analysis of the data collected during fieldwork campaigns and outlines the deployment of the beta version of Daily BlueFlux Predictions for South Florida, which will help generate a more accurate evaluation of flux for the many wetland ecosystems that exist beyond Florida’s borders.
“We’re trying to contribute to a better understanding of global carbon markets and inspire further and more ambitious investments in these critical stocks of blue carbon,” said Poulter. “First, we want to scale this work to the Caribbean, where we have these great maps of mangrove distribution but limited data on flux.”
An additional BlueFlux fieldwork deployment is slated for 2026, with plans to make flux measurements above sites targeted by the state for upcoming restoration initiatives, such as the Everglades Agricultural Area Environmental Protection District. In the Agricultural Area, construction is underway on a series of reservoirs that will store excess water during wet seasons and provide a reserve source of water for wildlife and residents during dry seasons. As the landscape evolves, BlueFlux will help local officials evaluate how Florida’s wetlands are responding to efforts designed to protect the state’s most precious natural resource – and all those who depend on it.
Nathan Marder
NASA’s Goddard Space Flight Center/Global Science and Technology Inc.
nathan.marder@nasa.gov
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Last Updated Nov 12, 2024 Related Terms
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By NASA
MuSat2 at Vandenberg Air Force Base, prior to launch. MuSat2 leverages a dual-frequency science antenna developed with support from NASA to measure phenomena such as ocean wind speed. Muon Space A science antenna developed with support from NASA’s Earth Science Technology Office (ESTO) is now in low-Earth orbit aboard MuSat2, a commercial remote-sensing satellite flown by the aerospace company Muon Space. The dual-frequency science antenna was originally developed as part of the Next Generation GNSS Bistatic Radar Instrument (NGRx). Aboard MuSat2, it will help measure ocean surface wind speed—an essential data point for scientists trying to forecast how severe a burgeoning hurricane will become.
“We’re very interested in adopting this technology and pushing it forward, both from a technology perspective and a product perspective,” said Jonathan Dyer, CEO of Muon.
Using this antenna, MuSat2 will gather signals transmitted by navigation satellites as they scatter off Earth’s surface and back into space. By recording how those scattered navigation signals change as they interact with Earth’s surface, MuSat2 will provide meteorologists with data points they can use to study severe weather.
“We use the standard GPS signals you know—the navigation signals that work for your car and your cell phone,” explained Chris Ruf, director of the University of Michigan Space Institute and principal investigator for NGRx.
Ruf designed the entire NGRx system to be an updated version of the sensors on NASA’s Cyclone Global Navigation Satellite System (CYGNSS), another technology he developed with support from ESTO. Since 2016, data from CYGNSS has been a critical resource for people dedicated to forecasting hurricanes.
The science antenna aboard MuSat2 enables two key improvements to the original CYGNSS design. First, the antenna allows MuSat2 to gather measurements from satellites outside the U.S.-based GPS system, such as the European Space Agency’s Galileo satellites. This capability enables MuSat2 to collect more data as it orbits Earth, improving its assessments of conditions on the planet’s surface.
Second, whereas CYGNSS only collected cross-polar radar signals, the updated science antenna also collects co-polar radar signals. This additional information could provide improved information about soil moisture, sea ice, and vegetation. “There’s a whole lot of science value in looking at both polarization components scattering from the Earth’s surface. You can separate apart the effects of vegetation from the effects of surface, itself,” explained Ruf.
Hurricane Ida, as seen from the International Space Station. NASA-developed technology onboard MuSat2 will help supply the U.S. Air Force with critical data for producing reliable weather forecasts. NASA For Muon Space, this technology infusion has been helpful to the company’s business and science missions. Dallas Masters, Vice President of Muon’s Signals of Opportunity Program, explains that NASA’s investments in NGRx technology made it much easier to produce a viable commercial remote sensing satellite. According to Masters, “NGRx-derived technology allowed us to start planning a flight mission early in our company’s existence, based around a payload we knew had flight heritage.”
Dyer agrees. “The fact that ESTO proves out these measurement approaches – the technology and the instrument, the science that you can actually derive, the products from that instrument – is a huge enabler for companies like ours, because we can adopt it knowing that much of the physics risk has been retired,” he said.
Ultimately, this advanced antenna technology for measuring ocean surface wind speed will make it easier for researchers to turn raw data into actionable science products and to develop more accurate forecasts.
“Information is absolutely precious. When it comes to forecast models and trying to understand what’s about to happen, you have to have as good an idea as you can of what’s already happening in the real world,” said oceanographer Lew Gramer, an Associate Scientist with the Cooperative Institute For Marine And Atmospheric Studies and NOAA’s Hurricane Research Division.
Project Lead: Chris Ruf, University of Michigan
Sponsoring Organizations: NASA’s Earth Science Technology Office and Muon Space
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Last Updated Nov 12, 2024 Related Terms
CYGNSS (Cyclone Global Navigation Satellite System) Earth Science Earth Science Division Earth Science Technology Office Oceans Science-enabling Technology Technology Highlights Explore More
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