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The Marshall Star for July 31, 2024


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The Marshall Star for July 31, 2024

After completing its journey from NASA’s Michoud Assembly Facility in New Orleans aboard the Pegasus barge, teams with Exploration Ground Systems (EGS) transport the agency’s powerful SLS (Space Launch System) core stage to NASA’s Kennedy Space Center’s Vehicle Assembly Building in Florida on Tuesday, July 23, 2024. Once inside, SLS will be prepared for integration atop the mobile launcher ahead of the Artemis II launch.

SLS Core Stage Rolls Inside Vehicle Assembly Building at Kennedy

NASA’s SLS (Space Launch System) rocket core stage for the Artemis II mission is inside the Vehicle Assembly Building at the agency’s Kennedy Space Center.

Tugboats and towing vessels moved the barge and core stage 900-miles to the Florida spaceport from NASA’s Michoud Assembly Facility, where it was manufactured and assembled.

After completing its journey from NASA’s Michoud Assembly Facility in New Orleans aboard the Pegasus barge, teams with Exploration Ground Systems (EGS) transport the agency’s powerful SLS (Space Launch System) core stage to NASA’s Kennedy Space Center’s Vehicle Assembly Building in Florida on Tuesday, July 23, 2024. Once inside, SLS will be prepared for integration atop the mobile launcher ahead of the Artemis II launch.
After completing its journey from NASA’s Michoud Assembly Facility aboard the Pegasus barge, teams with Exploration Ground Systems transport the agency’s powerful SLS (Space Launch System) core stage to NASA’s Kennedy Space Center’s Vehicle Assembly Building on July 23.
NASA/Isaac Watson

Team members with NASA’s Exploration Ground Systems Program safely transferred the 212-foot-tall core stage from the agency’s Pegasus barge, which arrived at NASA Kennedy’s Complex 39 turn basin wharf on July 23, onto the self-propelled module transporter, which is used to move large elements of hardware. It was then rolled to the Vehicle Assembly Building transfer aisle where teams will process it until it is ready for rocket stacking operations.

In the coming months, teams will integrate the rocket core stage atop the mobile launcher with the additional Artemis II flight hardware, including the twin solid rocket boosters, launch vehicle stage adapter, and the Orion spacecraft.

The Artemis II test flight will be NASA’s first mission with crew under the Artemis campaign, sending NASA astronauts Victor Glover, Christina Koch, and Reid Wiseman, as well as CSA (Canadian Space Agency) astronaut Jeremy Hansen, on a 10-day journey around the Moon and back.

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Take 5 with Chris Calfee

By Wayne Smith

Ask Chris Calfee about his favorite memory from his 38-year career at NASA’s Marshall Space Flight Center and you’ll discover it’s a difficult question to answer.

That’s because there have been many memories.

Chris Calfee is the SLS Spacecraft Payload Integration and Evolution element manager.
Chris Calfee is the SLS Spacecraft Payload Integration and Evolution element manager.
NASA/Charles Beason

Calfee was the integrator for the upper stage spacecraft for the Marshall-led Chandra X-Ray Observatory, which marked its 25th launch anniversary July 23. He’s worked with Demonstration of Autonomous Rendezvous Technology (DART), a technology mission aimed at demonstrating that a spacecraft could independently rendezvous with an orbiting satellite without human intervention. Calfee was the booster manager for the Ares I-X test flight, which he points to as another career highlight.

And then there’s his favorite memory – working with NASA’s SLS (Space Launch System) rocket and watching the 2022 Artemis I launch from NASA’s Kennedy Space Center.

I’ve been fortunate in my career to have the opportunities I’ve had with NASA,” said Calfee, the SLS Spacecraft Payload Integration and Evolution (SPIE) element manager. “Seeing the Chandra mission fly and the success it has had is awesome. Being able to work DART from cradle to grave, including its flight, was unforgettable. But I’d have to say being able to represent the SLS SPIE Element Office at Kennedy’s Launch Control Center and seeing Artemis I light up the night sky is the proudest moment.”

As the SLS Spacecraft/Payload Integration and Evolution element manager, Calfee’s responsibilities include overseeing the development and delivering key adapter hardware for SLS rockets that will power the first crewed Artemis missions and first flight of SLS in its evolved Block 1B configuration. The hardware includes the launch vehicle stage adapter, interim cryogenic propulsion stage, and the Orion stage adapter – and the universal stage adapter for SLS Block 1B. The SPIE Element Office serves a key role in the successful execution of the SLS mission, both for the initial launch capability as well as the evolution of subsequent rocket configurations.

NASA moved a step closer to the Artemis II launch with the July shipment of the SLS core stage to Kennedy from the agency’s Michoud Assembly Facility. Calfee and his team have the adapters complete for Artemis II and will soon ship them to Kennedy for launch preparations. As work advances toward Artemis II, Calfee looks back on the Artemis I launch as a “surreal experience.” But he put his celebration on hold as he watched the initial moments of the flight.

“The pressure was on the SPIE hardware to finish the job for SLS as we tracked the successful booster burn and separation, and then the core stage’s excellent performance,” said Calfee, who is from Newport, Tennessee, and a graduate of the University of Tennessee. “The interim cryogenic propulsion (ICPS) stage 20-minute burn was approximately one and a half hours after launch, followed by Orion spacecraft separation from the ICPS and Orion stage adapter, the most critical event of the mission from my perspective. It was another huge relief to see the ICPS burn and the Orion separation event go flawlessly.”

Calfee pauses for a photo in front of the SLS rocket ahead of the Artemis I launch in 2022.
Calfee pauses for a photo in front of the SLS rocket ahead of the Artemis I launch in 2022.
NASA/Courtesy of Chris Calfee

Memorable indeed.

Question: Looking ahead to Artemis II and the Artemis campaign, what excites you most about the future of human space exploration and your team’s role it?

Calfee: For me personally, it is exciting just to be a part of the future of human space flight and having the opportunity to influence that future. With respect to the SPIE team, it’s a similar feeling. Having the opportunity to lead a team that has such a significant role and responsibility in our future is an awesome experience.

Question: Who or what drives/motivates you?

Calfee: The opportunity to make a difference, be a part of history, and lead and mentor our future leaders.

Question: Who or what inspired you to pursue an education/career that led you to NASA and Marshall?

Calfee: My parents were my inspiration and provided me the opportunity to pursue my education. Although I followed the space program as a kid, specifically the Apollo program and Moon landings, I never dreamed that I would actually have the opportunity to work for NASA. I found my way to NASA via an on-campus interview job fair, was invited to Marshall for a follow-up interview, and it became an easy decision when an offer was made.

Question: What advice do you have for employees early in their NASA career or those in new leadership roles?

Calfee: For those early in their career, keep an open mind and be willing to take on new challenges. Diversify the resume. For those in new leadership roles, never get complacent. The moment you think you have it all figured out, something will surprise and humble you. I love the quote, “Get comfortable being uncomfortable,” because I guarantee as a leader, you will experience many uncomfortable moments.

Question: What do you enjoy doing with your time while away from work?

Calfee: Spending time with my grandkids. I also enjoy homebrewing and wine making, and I probably spend too much time following and watching college sports.

Smith, a Media Fusion employee and the Marshall Star editor, supports the Marshall Office of Communications.

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Stars, Stripes, and STEM: Q&A with Former NASA Intern, Miss America

Team members at NASA’s Marshall Space Flight Center recently sat down with reigning Miss America, Madison Marsh. In addition to her crown, Marsh is a second lieutenant in the United States Air Force and a former intern who contributed to astrophysics research at Marshall. Watch to learn more about her experience studying gamma-ray bursts and hear what advice she has for anyone interested in a STEM career. (NASA)

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Thomas Brown Named Marshall’s Chief Engineer, Manager of Engineering Office

Thomas Brown has been named center chief engineer and manager of the Chief Engineering Office within the Engineering Directorate at NASA’s Marshall Space Flight Center, effective July 28.

Thomas M. Brown, NASA
Thomas Brown has been named center chief engineer and manager of the Chief Engineering Office within the Engineering Directorate at NASA’s Marshall Space Flight Center.
NASA

In his role, Brown will be responsible for assuring the technical excellence and success of all Marshall-assigned spacecraft, propulsion, science payload, life support, and mission systems. He will provide expert technical leadership in planning, directing, and executing research, technology, ground and flight systems design and development, production, integration, and sustaining engineering for the Space Launch System Program, Human Landing System Program, the Human Exploration Development and Operations Office, and the Science and Technology Office.

Brown previously served as director of the Propulsion Systems Department of the Engineering Directorate, since 2020. In this role, he managed a $68 million annual budget and oversaw a workforce responsible for new and ongoing design and development activities for the propulsion components and systems at Marshall and other NASA centers.

As the capability lead for In-Space Transportation Systems from 2018-2020, Brown led the Systems Capability Leadership Team of system-specific subject matter experts from across the agency for the in-space transportation system’s disciplines, which support NASA’s robotic and human exploration missions. From 2014 to 2018, he was the NASA Technical Fellow for Propulsion and the NASA Propulsion Capability Lead, the agency’s most senior propulsion subject matter expert.

Between 2005 and 2014, Brown served as chief of two divisions within the Propulsion Systems Department, as well as technical advisor to the director of the Propulsion Systems Department at Marshall, where he assisted in internal technology investment planning and served in agency and cross-government level assignments. In 2007, he completed a one-year developmental assignment at Glenn Research Center as acting deputy manager of the Advanced Capabilities Project Office.

Brown began his NASA career at Marshall in 1999 as an aerospace engineer in the Space Transportation Directorate, performing propulsion systems analysis and integration. Initially working design, analysis, and integration of the X-34 Main Propulsion System and the Fastrac/MC-1 rocket engine, Brown’s activities quickly expanded into a broad range of propulsion technology development efforts. He served as chief engineer for several of these efforts during both the Second Generation Reusable Launch Vehicle Program and the Next Generation Launch Technology Program. Specific projects included the Main Propulsion and Auxiliary Propulsion Systems Technology Project and the ISTAR, Rocket Based Combined Cycle technology project.

Brown received a bachelor’s degree in physics from Allegheny College in Meadville, Pennsylvania, before earning his master’s and doctoral degrees in mechanical engineering from Vanderbilt University. He holds a U.S. patent and has published more than 30 refereed journal publications, book sections, and conference proceedings related to fundamental combustion, advanced measurement techniques, propulsion technology, and propulsion systems analysis and integration.

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Marshall Deputy Director Rae Ann Meyer Honored During Huntsville City Football Club Space Night

on-field.jpg?w=1536

NASA Marshall Deputy Director Rae Ann Meyer waves to a crowd of more than 4,000 fans at the Wicks Family Field at Joe Davis Stadium in Huntsville on July 27 during halftime of the soccer match between Huntsville City Football Club and Atlanta United 2. Meyer was honored as the “Hero of the Match,” recognizing her leadership and accomplishments in 35 years of service to the agency. (NASA/Taylor Goodwin)

inside-exhibits.jpg?w=1545

Representatives from 10 Marshall programs and projects staffed booths and exhibits at the stadium throughout the match, sharing details of their respective work to thousands of guests. (NASA/Taylor Goodwin)

outside-display.jpg?w=1545

Marshall’s exhibit footprint began outside of the stadium, welcoming soccer and space fans to the stadium with inflatables and educational materials. (NASA/Taylor Goodwin)

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NASA Supports Burst Test for Orbital Reef Commercial Space Station

An element of a NASA-funded commercial space station, Orbital Reef, under development by Blue Origin and Sierra Space, recently completed a full-scale ultimate burst pressure test as part of the agency’s efforts for new destinations in low Earth orbit.

This milestone is part of a NASA Space Act Agreement awarded to Blue Origin in 2021. Orbital Reef includes elements provided by Sierra Space, including the LIFE (Large Integrated Flexible Environment) habitat structure.

A photograph showing Sierra Space’s LIFE habitat following a full-scale ultimate burst pressure test at NASA’s Marshall Space Flight Center in Huntsville, Alabama
Sierra Space’s LIFE habitat following a full-scale ultimate burst pressure test at NASA’s Marshall Space Flight Center.
Sierra Space

Teams conducted the burst test on Sierra Space’s LIFE habitat structure using testing capabilities at NASA’s Marshall Space Flight Center. The inflatable habitat is fabricated from high-strength webbings and fabric that form a solid structure once pressurized. The multiple layers of soft goods materials that make up the shell are compactly stowed in a payload fairing and inflated when ready for use, enabling the habitat to launch on a single rocket.

“This is an exciting test by Sierra Space for Orbital Reef, showing industry’s commitment and capability to develop innovative technologies and solutions for future commercial destinations,” said Angela Hart, manager of NASA’s Commercial Low Earth Orbit Development Program at the agency’s Johnson Space Center. “Every successful development milestone by our partners is one more step to achieving our goal of enabling commercial low Earth orbit destinations and expanding the low Earth orbit marketplace.”

The pressurization to failure during the test demonstrated the habitat’s capabilities and provided the companies with critical data supporting NASA’s inflatable softgoods certification guidelines, which recommend a progression of tests to evaluate these materials in relevant operational environments and understand the failure modes.

Demonstrating the habitat’s ability to meet the recommended factor of safety through full-scale ultimate burst pressure testing is one of the primary structural requirements on a soft goods article, such as Sierra Space’s LIFE habitat, seeking flight certification.

Prior to this recent test, Sierra Space conducted its first full-scale ultimate burst pressure test on the LIFE habitat at Marshall in December 2023. Additionally, Sierra Space previously completed subscale tests, first at NASA’s Johnson Space Center and then at Marshall as part of ongoing development and testing of inflatable habitation architecture.

NASA supports the design and development of multiple commercial space stations, including Orbital Reef, through funded and unfunded agreements. The current design and development phase will be followed by the procurement of services from one or more companies.

NASA’s goal is to achieve a strong economy in low Earth orbit where the agency can purchase services as one of many customers to meet its science and research objectives in microgravity. NASA’s commercial strategy for low Earth orbit will provide the government with reliable and safe services at a lower cost, enabling the agency to focus on Artemis missions to the Moon in preparation for Mars while also continuing to use low Earth orbit as a training and proving ground for those deep space missions.

Learn more about NASA’s commercial space strategy.

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DART Mission Sheds New Light on Target Binary Asteroid System

In studying data collected from NASA’s DART (Double Asteroid Redirection Test) mission, which in 2022 sent a spacecraft to intentionally collide with the asteroid moonlet Dimorphos, the mission’s science team has discovered new information on the origins of the target binary asteroid system and why the DART spacecraft was so effective in shifting Dimorphos’ orbit. 

In five recently published papers in Nature Communications, the team explored the geology of the binary asteroid system, comprising moonlet Dimorphos and parent asteroid Didymos, to characterize its origin and evolution and constrain its physical characteristics. 

The various geological features observed on Didymos helped researchers tell the story of Didymos’ origins. The asteroid’s triangular ridge (first panel from left), and the so-called smooth region, and its likely older, rougher “highland” region (second panel from left) can be explained through a combination of slope processes controlled by elevation (third panel from left). The fourth panel shows the effects of spin-up disruption that Didymos likely underwent to form Dimorphos.
The various geological features observed on Didymos helped researchers tell the story of Didymos’ origins. The asteroid’s triangular ridge (first panel from left), and the so-called smooth region, and its likely older, rougher “highland” region (second panel from left) can be explained through a combination of slope processes controlled by elevation (third panel from left). The fourth panel shows the effects of spin-up disruption that Didymos likely underwent to form Dimorphos.
Johns Hopkins APL/Olivier Barnouin

“These findings give us new insights into the ways that asteroids can change over time,” said Thomas Statler, lead scientist for Solar System Small Bodies at NASA Headquarters. “This is important not just for understanding the near-Earth objects that are the focus of planetary defense, but also for our ability to read the history of our Solar System from these remnants of planet formation. This is just part of the wealth of new knowledge we’ve gained from DART.”

Olivier Barnouin and Ronald-Louis Ballouz of Johns Hopkins Applied Physics Laboratory (APL) in Laurel, Maryland, led a paper that analyzed the geology of both asteroids and drew conclusions about their surface materials and interior properties. From images captured by DART and its accompanying LICIACube cubesat – contributed by the Italian Space Agency (ASI), the team observed the smaller asteroid Dimorphos’ topography, which featured boulders of varying sizes. In comparison, the larger asteroid Didymos was smoother at lower elevations, though rocky at higher elevations, with more craters than Dimorphos. The authors inferred that Dimorphos likely spun off from Didymos in a large mass shedding event.

There are natural processes that can accelerate the spins of small asteroids, and there is growing evidence that these processes may be responsible for re-shaping these bodies or even forcing material to be spun off their surfaces.

Analysis suggested that both Didymos and Dimorphos have weak surface characteristics, which led the team to posit that Didymos has a surface age 40–130 times older than Dimorphos, with the former estimated to be 12.5 million years and the latter less than 300,000 years old. The low surface strength of Dimorphos likely contributed to DART’s significant impact on its orbit.

“The images and data that DART collected at the Didymos system provided a unique opportunity for a close-up geological look of a near-Earth asteroid binary system,” said Barnouin. “From these images alone, we were able to infer a great deal of information on geophysical properties of both Didymos and Dimorphos and expand our understanding on the formation of these two asteroids. We also better understand why DART was so effective in moving Dimorphos.”

Based on the internal and surface properties described in Barnouin et al. (2024), this video demonstrates how the spin-up of asteroid Didymos could have led to the growth of its equatorial ridge and the formation of the smaller asteroid Dimorphos, seen orbiting the former near the end of the clip. Particles are colored according to their speeds, with the scale shown at the top, along with the continually changing spin period of Didymos.
University of Michigan/Yun Zhang and Johns Hopkins APL/Olivier Barnouin

Maurizio Pajola, of the National Institute for Astrophysics (INAF) in Rome, and co-authors led a paper comparing the shapes and sizes of the various boulders and their distribution patterns on the two asteroids’ surfaces. They determined the physical characteristics of Dimorphos indicate it formed in stages, likely of material inherited from its parent asteroid Didymos. That conclusion reinforces the prevailing theory that some binary asteroid systems arise from shed remnants of a larger primary asteroid accumulating into a new asteroid moonlet.

Alice Lucchetti, also of INAF, and colleagues found that thermal fatigue – the gradual weakening and cracking of a material caused by heat – could rapidly break up boulders on the surface of Dimorphos, generating surface lines and altering the physical characteristics of this type of asteroid more quickly than previously thought. The DART mission was likely the first observation of such a phenomenon on this type of asteroid. 

Supervised by researcher Naomi Murdoch of ISAE-SUPAERO in Toulouse, France, and colleagues, a paper led by students Jeanne Bigot and Pauline Lombardo determined Didymos’ bearing capacity – the surface’s ability to support applied loads – to be at least 1,000 times lower than that of dry sand on Earth or lunar soil. This is considered an important parameter for understanding and predicting the response of a surface, including for the purposes of displacing an asteroid.

Colas Robin, also of ISAE-SUPAERO, and co-authors analyzed the surface boulders on Dimorphos, comparing them with those on other rubble pile asteroids, including ItokawaRyugu, and Bennu. The researchers found the boulders shared similar characteristics, suggesting all these types of asteroids formed and evolved in a similar fashion. The team also noted that the elongated nature of the boulders around the DART impact site implies that they were likely formed through impact processing.

These latest findings form a more robust overview of the origins of the Didymos system and add to the understanding of how such planetary bodies were formed. As ESA’s (European Space Agency) Hera mission prepares to revisit DART’s collision site in 2026 to further analyze the aftermath of the first-ever planetary defense test, this research provides a series of tests for what Hera will find and contributes to current and future exploration missions while bolstering planetary defense capabilities. 

Johns Hopkins APL managed the DART mission for NASA’s Planetary Defense Coordination Office as a project of the agency’s Planetary Missions Program Office, which is at NASA’s Marshall Space Flight Center. NASA provided support for the mission from several centers, including the Jet Propulsion Laboratory, Goddard Space Flight Center, Johnson Space Center, Glenn Research Center, and Langley Research Center. 

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Fermi Finds New Feature in Brightest Gamma-Ray Burst Yet Seen

In October 2022, astronomers were stunned by what was quickly dubbed the BOAT — the brightest-of-all-time gamma-ray burst (GRB). Now an international science team reports that data from NASA’s Fermi Gamma-ray Space Telescope reveals a feature never seen before.

“A few minutes after the BOAT erupted, Fermi’s Gamma-ray Burst Monitor recorded an unusual energy peak that caught our attention,” said lead researcher Maria Edvige Ravasio at Radboud University in Nijmegen, Netherlands, and affiliated with Brera Observatory, part of INAF (the Italian National Institute of Astrophysics) in Merate, Italy. “When I first saw that signal, it gave me goosebumps. Our analysis since then shows it to be the first high-confidence emission line ever seen in 50 years of studying GRBs.”

A jet of particles moving at nearly light speed emerges from a massive star in this artist’s concept. The star’s core ran out of fuel and collapsed into a black hole. Some of the matter swirling toward the black hole was redirected into dual jets firing in opposite directions. We see a gamma-ray burst when one of these jets happens to point directly at Earth.
A jet of particles moving at nearly light speed emerges from a massive star in this artist’s concept. The star’s core ran out of fuel and collapsed into a black hole. Some of the matter swirling toward the black hole was redirected into dual jets firing in opposite directions. We see a gamma-ray burst when one of these jets happens to point directly at Earth.
NASA

paper about the discovery appears in the July 26 edition of the journal Science.

When matter interacts with light, the energy can be absorbed and reemitted in characteristic ways. These interactions can brighten or dim particular colors (or energies), producing key features visible when the light is spread out, rainbow-like, in a spectrum. These features can reveal a wealth of information, such as the chemical elements involved in the interaction. At higher energies, spectral features can uncover specific particle processes, such as matter and antimatter annihilating to produce gamma rays.

“While some previous studies have reported possible evidence for absorption and emission features in other GRBs, subsequent scrutiny revealed that all of these could just be statistical fluctuations. What we see in the BOAT is different,” said coauthor Om Sharan Salafia at INAF-Brera Observatory in Milan, Italy. “We’ve determined that the odds this feature is just a noise fluctuation are less than one chance in half a billion.”

GRBs are the most powerful explosions in the cosmos and emit copious amounts of gamma rays, the highest-energy form of light. The most common type occurs when the core of a massive star exhausts its fuel, collapses, and forms a rapidly spinning black hole. Matter falling into the black hole powers oppositely directed particle jets that blast through the star’s outer layers at nearly the speed of light. We detect GRBs when one of these jets points almost directly toward Earth.

The BOAT, formally known as GRB 221009A, erupted Oct. 9, 2022, and promptly saturated most of the gamma-ray detectors in orbit, including those on Fermi. This prevented them from measuring the most intense part of the blast. Reconstructed observations, coupled with statistical arguments, suggest the BOAT, if part of the same population as previously detected GRBs, was likely the brightest burst to appear in Earth’s skies in 10,000 years.

The brightest gamma-ray burst yet recorded gave scientists a new high-energy feature to study. Learn what NASA’s Fermi mission saw, and what this feature may be telling us about the burst’s light-speed jets. (NASA’s Goddard Space Flight Center)

The putative emission line appears almost 5 minutes after the burst was detected and well after it had dimmed enough to end saturation effects for Fermi. The line persisted for at least 40 seconds, and the emission reached a peak energy of about 12 MeV (million electron volts). For comparison, the energy of visible light ranges from 2 to 3 electron volts.

So what produced this spectral feature? The team thinks the most likely source is the annihilation of electrons and their antimatter counterparts, positrons.

“When an electron and a positron collide, they annihilate, producing a pair of gamma rays with an energy of 0.511 MeV,” said coauthor Gor Oganesyan at Gran Sasso Science Institute and Gran Sasso National Laboratory in L’Aquila, Italy. “Because we’re looking into the jet, where matter is moving at near light speed, this emission becomes greatly blueshifted and pushed toward much higher energies.”

If this interpretation is correct, to produce an emission line peaking at 12 MeV, the annihilating particles had to have been moving toward us at about 99.9% the speed of light.

“After decades of studying these incredible cosmic explosions, we still don’t understand the details of how these jets work,” noted Elizabeth Hays, the Fermi project scientist at NASA’s Goddard Space Flight Center. “Finding clues like this remarkable emission line will help scientists investigate this extreme environment more deeply.” 

The Fermi Gamma-ray Space Telescope is an astrophysics and particle physics partnership managed by Goddard. Fermi was developed in collaboration with the U.S. Department of Energy, with important contributions from academic institutions and partners in France, Germany, Italy, Japan, Sweden, and the United States.

NASA’s Marshall Space Flight Center is responsible for one of the instruments on the Fermi Gamma-ray Space Telescope – the Gamma-ray Burst Monitor, or GBM. The GBM studies gamma-ray bursts, the most powerful explosions in the universe, as well as other flashes of gamma rays. The GBM sees these bursts across the entire sky, and scientists are using its observations to learn more about the universe.

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      Jasmine Sirvent
      Ocean color remote sensing enables researchers to assess the quantity and physiology of life in the ocean, which is imperative to understanding ecosystem health and formulating accurate predictions. However, without proper methods to analyze hyperspectral data, correlations between spectral reflectance and physiological traits cannot be accurately derived. In this study, I explored different methods—single variable regression, partial least squares regressions (PLSR), and derivatives—in analyzing in situ Macrocystis pyrifera (giant kelp) off the coast of Santa Barbara, California in order to predict pigment concentrations from AVIRIS hyperspectral reflectance. With derivatives as a spectral diagnostic tool, there is evidence suggesting high versus low pigment concentrations could be diagnosed; however, the fluctuations were within 10 nm of resolution, thus AVIRIS would be unable to reliably detect them. Exploring a different method, I plotted in situ pigment measurements — chlorophyll a, fucoxanthin, and the ratio of fucoxanthin to chlorophyll a—against hyperspectral reflectance that was resampled to AVIRIS bands. PLSR proved to be a more successful model because of its hyperdimensional analysis capabilities in accounting for multiple wavelength bands, reaching R2 values of 0.67. Using this information, I constructed a model that predicts kelp pigments from simulated AVIRIS reflectance using a spatial time series of laboratory spectral measurements and photosynthetic pigment concentrations. These results have implications, not only for kelp, but many other photosynthetic organisms detectable by hyperspectral airborne or satellite sensors. With these findings, airborne optical data could possibly predict a plethora of other biogeochemical traits. Potentially, this research would permit scientists to acquire data analogous to in situ measurements about floating matters that cannot financially and pragmatically be accessed by anything other than a remote sensor.

      Isabelle Cobb
      Correlations Between SSHa and Chl-a Concentrations in the Northern South China Sea
      Isabelle Cobb
      Sea surface height anomalies (SSHa)–variations in sea surface height from climatological averages–occur on seasonal timescales due to coastal upwelling and El Niño-Southern Oscillation (ENSO) cycles. These anomalies are heightened when upwelling plumes bring cold, nutrient-rich water to the surface, and are particularly strong along continental shelves in the Northern South China Sea (NSCS). This linkage between SSHa and nutrient availability has interesting implications for changing chlorophyll-a (chl-a) concentrations, a prominent indicator of phytoplankton biomass that is essential to the health of marine ecosystems. Here, we evaluate the long-term (15 years) relationship between SSHa and chl-a, in both satellite remote sensing data and in situ measurements. Level 3 SSHa data from Jason 1/2/3 satellites and chl-a data from MODIS Aqua were acquired and binned to monthly resolution. We found a significant inverse correlation between SSHa and chl-a during upwelling months in both the remote sensing (Spearman’s R=-0.57) and in situ data, with higher resolution in situ data from ORAS4 (an assimilation of buoy observations from 2003-2017) showing stronger correlations (Spearman’s R=-0.75). In addition, the data reveal that the magnitude of SSH increases with time during instances of high correlation, possibly indicating a trend of increased SSH associated with reduced seasonal chl-a concentrations. Thus, this relationship may inform future work predicting nutrient availability and threats to marine ecosystems as climate change continues to affect coastal sea surface heights.

      Alyssa Tou
      Exploring Coastal Sea Surface Temperature Anomalies and their effect on Coastal Fog through analyzing Plant Phenology
      Alyssa Tou
      Marine heat waves (MHW) have been increasing in frequency, duration and intensity, giving them substantial potential to influence ecosystems. Do these MHWs sufficiently enhance coastal precipitation such that plant growth is impacted? Recently, the Northeast Pacific experienced a long, intense MHW in 2014/2015, and another short, less intense MHW in 2019/2020. Here we investigate how the intensity and duration of MHWs influence the intensity and seasonal cycle of three different land cover types (‘grass’, ‘trees’, and a combination of both ‘combined’’) to analyze plant phenology trends in Big Sur, California. We hypothesize that longer intense MHWs decrease the ocean’s evaporative capacity, decreasing fog, thus lowering plant productivity, as measured by Normalized Difference Vegetation Index (NDVI). Sea surface temperature (SST) and NDVI data were collected from the NOAA Coral Reef Watch, and NASA MODIS/Terra Vegetation Indices 16-Day L3 Global 250m products respectively. Preliminary results show no correlation (R2=0.02) between SSTa and combined NDVI values and no correlation (R2=0.01) between SST and NDVI. This suggests that years with anomalously high SST do not significantly impact plant phenology. During the intense and long 2014/2015 MHW, peak NDVI values for ‘grass’ and ‘combined’ pixels were 2.0 and 1.7 standard deviations above the climatological average, while the shorter 2019/2020 MHW saw higher peaks of 3.2 and 2.4 standard deviations. However, the ‘grass’, ‘tree’ and ‘combined’ NDVI anomalies were statistically insignificant during both MHWs, showing that although NDVI appeared to increase during the shorter and less intense MHW, these values may be attributed to other factors. The data qualitatively suggest that MHW’s don’t impact the peak NDVI date, but more data at higher temporal resolution are necessary. Further research will involve analyzing fog indices and exploring confounding variables impacting NDVI, such as plant physiology, anthropogenic disturbance, and wildfires. In addition, it’s important to understand to what extent changes in NDVI are attributed to the driving factors of MHWs or the MHWs themselves. Ultimately, mechanistically understanding the impacts MHW intensity and duration have on terrestrial ecosystems will better inform coastal community resilience.


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      Last Updated Nov 22, 2024 Related Terms
      General Explore More
      10 min read SARP East 2024 Atmospheric Science Group
      Article 21 mins ago 10 min read SARP East 2024 Hydroecology Group
      Article 21 mins ago 11 min read SARP East 2024 Terrestrial Fluxes Group
      Article 22 mins ago View the full article
    • By NASA
      10 min read
      Preparations for Next Moonwalk Simulations Underway (and Underwater)
      Return to 2024 SARP Closeout Faculty Advisors:
      Dr. Guanyu Huang, Stony Brook University
      Graduate Mentor:
      Ryan Schmedding, McGill University

      Ryan Schmedding, Graduate Mentor
      Ryan Schmedding, graduate mentor for the 2024 SARP Atmospheric Science group, provides an introduction for each of the group members and shares behind-the scenes moments from the internship.
      Danielle Jones
      Remote sensing of poor air quality in mountains: A case study in Kathmandu, Nepal
      Danielle Jones
      Urban activity produces particulate matter in the atmosphere known as aerosol particles. These aerosols can negatively affect human health and cause changes to the climate system. Measures for aerosols include surface level PM2.5 concentration and aerosol optical depth (AOD). Kathmandu, Nepal is an urban area that rests in a valley on the edge of the Himalayas and is home to over three million people. Despite the prevailing easterly winds, local aerosols are mostly concentrated in the valley from the residential burning of coal followed by industry. Exposure to PM2.5 has caused an estimated ≥8.6% of deaths annually in Nepal. We paired NASA satellite AOD and elevation data, model  meteorological data, and local AirNow PM2.5 and air quality index (AQI) data to determine causes of variation in pollutant measurement during 2023, with increased emphasis on the post-monsoon season (Oct. 1 – Dec. 31). We see the seasonality of meteorological data related to PM2.5 and AQI. During periods of low temperature, low wind speed, and high pressure, PM2.5 and AQI data slightly diverge. This may indicate that temperature inversions increase surface level concentrations of aerosols but have little effect on the total air column. The individual measurements of surface pressure, surface temperature, and wind speed had no observable correlation to AOD (which was less variable than PM2.5 and AQI over the entire year). Elevation was found to have no observable effect on AOD during the period of study. Future research should focus on the relative contributions of different pollutants to the AQI to test if little atmospheric mixing causes the formation of low-altitude secondary pollutants in addition to PM2.5 leading to the observed divergence in AQI and PM2.5.

      Madison Holland
      Analyzing the Transport and Impact of June 2023 Canadian Wildfire Smoke on Surface PM2.5 Levels in Allentown, Pennsylvania
      Madison Holland
      The 2023 wildfire season in Canada was unparalleled in its severity. Over 17 million hectares burned, the largest area ever burned in a single season. The smoke from these wildfires spread thousands of kilometers, causing a large population to be exposed to air pollution. Wildfires can release a variety of air pollutants, including fine particulate matter (PM2.5). PM2.5 directly affects human health – exposure to wildfire-related PM2.5 has been associated with respiratory issues such as the exacerbation of asthma and chronic obstructive pulmonary disease. In June 2023, smoke from the Canadian wildfires drifted southward into the United States. The northeastern United States reported unhealthy levels of air quality due to the transportation of the smoke. In particular, Pennsylvania reported that Canadian wildfires caused portions of the state to have “Hazardous” air quality. Our research focused on how Allentown, PA experienced hazardous levels of air quality from this event. To analyze the concentrations of PM2.5 at the surface level, NASA’s Hazardous Air Quality Ensemble System (HAQES) and the EPA’s Air Quality System (AQS) ground-based site data were utilized. By comparing HAQES’s forecast of hazardous air quality events with recorded daily average PM2.5 with the EPA’s AQS, we were able to compare how well the ensemble system was at predicting total PM2.5 during unhealthy air quality days. NOAA’s Hybrid Single-Particle Lagrangian Integrated Trajectory model, pyrsig, and the Canadian National Fire Database were used. These datasets revealed the trajectory of aerosols from the wildfires to Allentown, Pennsylvania, identified the densest regions of the smoke plumes, and provided a map of wildfire locations in southeastern Canada. By integrating these datasets, we traced how wildfire smoke transported aerosols from the source at the ground level.

      Michele Iraci
      Trends and Transport of Tropospheric Ozone From New York City to Connecticut in the Summer of 2023
      Michele Iraci
      Tropospheric Ozone, or O₃, is a criteria pollutant contributing to most of Connecticut and New York City’s poor air quality days. It has adverse effects on human health, particularly for high-risk individuals. Ozone is produced by nitrogen oxides and volatile organic compounds from fuel combustion reacting with sunlight. The Ozone Transport Region (OTR) is a collection of states in the Northeast and Mid-Atlantic United States that experience cross-state pollution of O₃. Connecticut has multiple days a year where O₃ values exceed the National Ambient Air Quality Standards requiring the implementation of additional monitoring and standards because it falls in the OTR. Partially due to upstream transport from New York City, Connecticut experiences increases in O₃ concentrations in the summer months. Connecticut has seen declines in poor air quality days from O₃ every year due to the regulations on ozone and its precursors. We use ground-based Lidar, Air Quality System data, and a back-trajectory model to examine a case of ozone enhancement in Connecticut caused by air pollutants from New York between June and August 2023. In this time period, Connecticut’s ozone enhancement was caused by air pollutants from New York City. As a result, New York City and Connecticut saw similar O₃ spikes and decline trends. High-temperature days increase O₃ in both places, and wind out of the southwest may transport O₃ to Connecticut. Production and transport of O₃ from New York City help contribute to Connecticut’s poor air quality days, resulting in the need for interstate agreements on pollution management.

      Stefan Sundin
      Correlations Between the Planetary Boundary Layer Height and the Lifting Condensation Level
      Stefan Sundin
      The Planetary Boundary Layer (PBL) characterizes the lowest layer in the atmosphere that is coupled with diurnal heating at the surface. The PBL grows during the day as solar heating causes pockets of air near the surface to rise and mix with cooler air above. Depending on the type of terrain and surface albedo that receives solar heating, the depth of the PBL can vary to a great extent. This makes PBL height (PBLH) a difficult variable to quantify spatially and temporally. While several methods have been used to obtain the PBLH such as wind profilers and lidar techniques, there is still a level of uncertainty associated with PBLH. One method of predicting seasonal PBLH fluctuation and potentially lessening uncertainty that will be discussed in this study is recognizing a correlation in PBLH with the lifting condensation level (LCL). Like the PBL, the LCL is used as a convective parameter when analyzing upper air data, and classifies the height in the atmosphere at which a parcel becomes saturated when lifted by a forcing mechanism, such as a frontal boundary, localized convergence, or orographic lifting. A reason to believe that PBLH and LCL are interconnected is their dependency on both the amount of surface heating and moisture that is present in the environment. These thermodynamic properties are of interest in heavily populated metropolitan areas within the Great Plains, as they are more susceptible to severe weather outbreaks and associated economic losses. Correlations between PBLH and LCL over the Minneapolis-St. Paul metropolitan statistical area during the summer months of 2019-2023 will be discussed.

      Angelica Kusen
      Coupling of Chlorophyll-a Concentrations and Aerosol Optical Depth in the Subantarctic Southern Ocean and South China Sea (2019-2021)
      Angelica Kusen
      Air-sea interactions form a complex feedback mechanism, whereby aerosols impact physical and biogeochemical processes in marine environments, which, in turn, alter aerosol properties. One key indicator of these interactions is chlorophyll-a (Chl-a), a pigment common to all phytoplankton and a widely used proxy for primary productivity in marine ecosystems. Phytoplankton require soluble nutrients and trace metals for growth, which typically come from oceanic processes such as upwelling. These nutrients can also be supplied via wet and dry deposition, where atmospheric aerosols are removed from the atmosphere and deposited into the ocean. To explore this interaction, we analyze the spatial and temporal variations of satellite-derived chl-a and AOD, their correlations, and their relationship with wind patterns in the Subantarctic Southern Ocean and the South China Sea from 2019 to 2021, two regions with contrasting environmental conditions.
      In the Subantarctic Southern Ocean, a positive correlation (r²= 0.26) between AOD and Chl-a was found, likely due to dust storms following Austrian wildfires. Winds deposit dust aerosols rich in nutrients, such as iron, to the iron-limited ocean, enhancing phytoplankton photosynthesis and increasing chl-a. In contrast, the South China Sea showed no notable correlation (r² = -0.02) between AOD and chl-a. Decreased emissions due to COVID-19 and stricter pollution controls likely reduced the total AOD load and shifted the composition of aerosols from anthropogenic to more natural sources.
      These findings highlight the complex interrelationship between oceanic biological activity and the chemical composition of the atmosphere, emphasizing that atmospheric delivery of essential nutrients, such as iron and phosphorus, promotes phytoplankton growth. Finally, NASA’s recently launched PACE mission will contribute observations of phytoplankton community composition at unprecedented scale, possibly enabling attribution of AOD levels to particular groups of phytoplankton.

      Chris Hautman
      Estimating CO₂ Emission from Rocket Plumes Using in Situ Data from Low Earth Atmosphere
      Chris Hautman
      Rocket emissions in the lower atmosphere are becoming an increasing environmental concern as space exploration and commercial satellite launches have increased exponentially in recent years. Rocket plumes are one of the few known sources of anthropogenic emissions directly into the upper atmosphere. Emissions in the lower atmosphere may also be of interest due to their impacts on human health and the environment, in particular, ground level pollutants transported over wildlife protected zones, such as the Everglades, or population centers near launch sites. While rockets are a known source of atmospheric pollution, the study of rocket exhaust is an ongoing task. Rocket exhaust can have a variety of compositions depending on the type of engine, the propellants used, including fuels, oxidizers, and monopropellants, the stoichiometry of the combustion itself also plays a role. In addition, there has been increasing research into compounds being vaporized in atmospheric reentry. These emissions, while relatively minimal compared to other methods of travel, pose an increasing threat to atmospheric stability and environmental health with the increase in human space activity. This study attempts to create a method for estimating the total amount of carbon dioxide released by the first stage of a rocket launch relative to the mass flow of RP-1, a highly refined kerosene (C₁₂H₂₆)), and liquid oxygen (LOX) propellants. Particularly, this study will focus on relating in situ CO₂ emission data from a Delta II rocket launch from Vandenberg Air Force Base on April 15, 1999, to CO₂ emissions from popular modern rockets, such as the Falcon 9 (SpaceX) and Soyuz variants (Russia). The findings indicate that the CO₂ density of any RP-1/LOX rocket is 6.9E-7 times the mass flow of the sum of all engines on the first stage. The total mass of CO₂ emitted can be further estimated by modeling the volume of the plume as cylindrical. Therefore, the total mass can be calculated as a function of mass flow and first stage main engine cutoff. Future CO₂ emissions on an annual basis are calculated based on these estimations and anticipated increases in launch frequency.


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      Last Updated Nov 22, 2024 Related Terms
      General Explore More
      8 min read SARP East 2024 Ocean Remote Sensing Group
      Article 21 mins ago 10 min read SARP East 2024 Hydroecology Group
      Article 21 mins ago 11 min read SARP East 2024 Terrestrial Fluxes Group
      Article 22 mins ago View the full article
    • By NASA
      10 min read
      Preparations for Next Moonwalk Simulations Underway (and Underwater)
      Return to 2024 SARP Closeout Faculty Advisors:
      Dr. Dom Ciruzzi, College of William & Mary
      Graduate Mentor:
      Marley Majetic, Pennsylvania State University

      Marley Majetic, Graduate Mentor
      Marley Majetic, graduate mentor for the 2024 SARP Hydroecology group, provides an introduction for each of the group members and shares behind-the scenes moments from the internship.
      Jordan DiPrima
      How are different land cover types affected by land subsidence on the U.S. Atlantic Coast?
      Jordan DiPrima
      Land subsidence is a frequently overlooked geologic hazard that is caused by natural processes and, more recently, anthropogenic stressors. The goal of this study is to observe subsidence trends and hotspots among land cover types on Virginia’s Eastern Shore and Long Island, New York. This study utilizes interferometric synthetic aperture radar, or InSAR, satellite data from Sentinel-1 to map vertical land motion from 2017 to 2023. Land cover data were sourced from Landsat 8 satellite imagery. Subsidence was mapped within the following land cover types on the Eastern Shore: urban, wetland, cropland, temperate or sub-polar grassland, temperate or sub-polar shrubland, mixed forest, and temperate or subpolar needleleaf forest. These land cover types have mean vertical velocities ranging from -0.2 mm/yr to -5.2 mm/yr. Results suggest that land subsidence is most severe in cropland areas on the Eastern Shore, with a mean vertical velocity of -5.2 mm/yr. In contrast, wetlands display the most subsidence on Long Island with a mean vertical velocity of -2.1 mm/yr. Long Island lacked distinct trends among land cover types and instead showed evidence of subsidence hotspots. These hotspots exist in the following land cover types: temperate or sub-polar grassland, barren lands, wetland, cropland, and temperate or sub-polar broadleaf deciduous forest. Overall, Eastern Shore croplands and Long Island wetlands were determined to be the most susceptible land cover types. These findings highlight regions at risk of sea level rise, flooding, and coastal erosion as a result of subsidence. With further research, we can map subsiding landscapes on a global scale to improve resource allocation and mitigation techniques.

      Isabelle Peterson
      Total Thermokarst Lake Changes on the Seward Peninsula, Alaska: 2016 to 2024
      Isabelle Peterson
      Thermokarst landscapes have and will continue to change as the arctic landscape warms due to climate change. Permafrost underlies much of these arctic landscapes, and as it melts, thermokarst landscapes are left behind. The Seward Peninsula in Alaska has an abundance of these landscapes, and thermokarst lakes are present in the northernmost portion. Several lakes have come and gone, but with increasing climate instability and warming of the area, there is a possibility of more permafrost melting, creating more of these lakes. To capture these changes, Harmonized Landsat Sentinel-2 (HLS) imagery were used to create annual lake maps of the northern portion of the Seward Peninsula from 2016 to 2024. Much of the methodology was informed from Jones et al. (2011); however, their study used eCognition, while the present study used ArcGIS Pro. This caused some differences in results likely due to the differences in software, satellite imagery, and the proposed study area. Lake number changes were observed annually. From this annual change, several 10 to 40 ha lakes disappeared and reappeared within the study period, along with smaller lakes filling in where larger lakes once were. Thermokarst lake drainage is a process described by Jones and Arp (2015) which has devastating geomorphological impacts on the surrounding area, creating large drainage troughs which diminish surrounding permafrost in a quick time frame. To capture these events and overall changes, satellite imagery is essential. This is especially true in remote regions which are hard to reach by foot and require flight missions to be scheduled over the area for aerial photography. However, LVIS and other higher resolution aerial instruments would provide higher accuracy when identifying smaller lakes, as satellite imagery does not accurately capture lakes below 1 ha in the study area. This assertion is made due to conflicting results compared to Jones et al (2011). While the methodologies of this study have been executed manually, Qin, Zhang, and Lu (2023) have proposed the idea of using Sentinel-2 imagery to map thermokarst lakes through automatic methods. While automatization has not yet been perfected, the potential is there and can be used to analyze thermokarst areas effectively. With more satellite imagery, annual, monthly, and potentially daily changes can be captured in favorable months to monitor changing landscapes in arctic regions. Thermokarst lakes have been changing, and monitoring them can help in the process of understanding the changing climate in arctic areas, especially through the lens melting permafrost.

      Emmanelle Cuasay
      Finding Refuge in Climate Crisis: Analyzing the Differences between Refugia and Non-Refugia in the Northern Philippines Using Remote Sensing
      Emmanelle Cuasay
      Refugia are areas that are characterized by stable environmental conditions that can act as a refuge for species as Earth’s climate warms. In this study, fourteen Harmonized Landsat Sentinel-2 images from February 2014 – March 2024 of the northern Philippines region were used. The region of interest is the terrestrial biome by Lake Taal. Normalized Difference Vegetation Index (NDVI) maps were created from all fourteen images to determine the NDVI 25th highest quartiles of the long-term average NDVI images and of a dry and wet year NDVI image. These values were then used to create refugia and non-refugia maps using ArcGIS Pro. Land cover data from Sentinel-2 and a digital elevation model (DEM), using the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), were plotted in ArcGIS Pro to determine the slope and aspect of the area. Global Ecosystems Dynamics Investigation (GEDI) data were used to look at forest height of the study area, and the distribution of forest height, slope, aspect, and elevation were plotted to determine their probability densities in refugia and non-refugia areas. Results of this study show increased biomass in refugia areas. This suggests that conservation practices are crucial to aid in the preservation of biodiversity and biomass within these refugia areas.

      Jayce Crayne
      Site-Based Observations of a Saharan Dust Storm’s Impacts on Evapotranspiration in North-Central Florida
      Jayce Crayne
      Saharan dust storms serve an important role in the western Atlantic’s climate in their contribution to Earth’s radiation budget, modulating sea surface temperatures (SSTs), fertilizing ecosystems, and suppressing cloud and precipitation patterns (Yuan et al., 2020). However, Saharan dust storms are expected to become less frequent in this region as SSTs continue to rise (Yuan et al., 2020). Predicting the climate response to this change requires a keen understanding of how the presence of these storms affect evapotranspiration (ET) and its indicators. This study utilizes site-based observational data from an AmeriFlux tower near Gainesville, FL recorded during a large dust storm in late June 2020. The storm’s progression was documented using satellite imagery from Aqua and Terra and aerosol optical depth (AOD) measurements from an Aerosol Robotic Network (AERONET) station co-located with the AmeriFlux tower. Indicators of ET such as surface air temperature, vapor pressure deficit, photosynthetic photon flux density, and net radiation were analyzed. Findings were compared to modeled ET and latent energy flux reanalysis data provided by the Global Land Data Assimilation System (GLDAS). Both model simulations and on-site observations support that ET decreased during the days dust concentrations were heaviest and for a short time thereafter. Cloud cover data adopted from meteorological aerodrome reports (METARs) provided by an automated surface observing system (ASOS) located in Gainesville showed that clouds were not a major contributor in decreasing ET during the days of heaviest dust. The results of this study show a considerable decrease in ET as a result of dust aerosols. Further research is necessary to determine whether changes in ET due to Saharan dust storms are significant enough to alter climates in the western Atlantic and, if so, what the climate response will be if the frequency of storms decreases.

      Brandon Wilson
      Predicting 2025 and 2028 dNBR and dNDIV for Csarf Smith River Complex / Evaluating the Effects of 2019 California Wildfire Fund
      Brandon Wilson
      Biodiverse regions across California remain vulnerable to harmful wildfires year round. Quantifying and measuring these regions’ wildfire resilience is necessary for understanding where/how to allocate environmental resources. Several ecological wildfire studies have been conducted utilizing artificial intelligence and remote sensing to analyze and predict biodiversity damage across wildfire prone regions, including Northern Algeria and Arkansas, USA. The current case study aims to analyze biodiversity damage from the 2023 Csarf Smith River Complex Fire in Six Rivers National Forest, California and predict the difference in Normalized Burn Ratio (dNBR) and difference in Normalized Difference Vegetation Index (dNDVI) for 2025 and 2028 using remote-sensing-based random forest (RF) regression. Furthermore, to observe, holistically, a practical method California has implemented to address state-wide wildfire damage, the 2019 California Wildfire Fund (AB 1054 and AB 111) was evaluated using the synthetic control method (SCM). For this case study, remote sensing data from the United States Geological Survey (USGS) and NASA (Landsat 9 Satellite C2 L2, TerraClimate and the Land Data Assimilation System) were utilized for processing relevant spectral indexes for the RF. Data from NOAA, Energy Information Agency, International Monetary Fund and Bureau of Economic Analysis were utilized as synthetic control datasets to evaluate the effects of the 2019 California Wildfire Fund. Elevated topography in this study area is susceptible to high severity burn effects, while less elevated topography burns less. This result affected dNBR and dNDVI predictions as elevated areas seemingly did not have strong resilience to rampant burns. This demonstrates a direct correlation to potential lower transpiration rates for elevated areas, warranting further analysis. Results of low variance, post-treatment, between the treated unit and the synthetic control unit, poses concern for the positive effect of the 2019 Wildfire Fund.

      Carrie Hashimoto
      Describing changes in evapotranspiration following the 2020 Creek Fire in the southern Sierra Nevada
      Carrie Hashimoto
      Climatic warming and high tree density have caused larger and more severe wildfires to occur in western United States forests over time. Wildfires affect both the hydrology and ecology of forests via alterations to the water balance (e.g., evapotranspiration, streamflow, infiltration, and more) and could shift vegetation communities and subsequent ecosystem structure and function. This project explores ecological characteristics of a landscape that predict the extent to which the Creek Fire in the southern Sierra Nevada has affected evapotranspiration. Strides in understanding of consequential evapotranspiration changes can create pathways to address emerging forest health challenges posed by similar western fires. For analysis, various remote sensing and modeled data were collected from OpenET, the North American Land Data Assimilation System, TerraClimate, Harmonized LandSat Sentinel-2 data, and the Shuttle Radar Topography Mission. Multiple linear regression and generalized additive models were constructed. Relative change in evapotranspiration served as the response variable. Model covariates included average temperature, total precipitation in the preceding months, average soil moisture, elevation, slope, aspect, northness, latitude, pre-fire normalized difference vegetation index (NDVI), and post-fire change in normalized burn ratio (dNBR). Best subset selection with cross validation demonstrated minimization of cross-validation error with a 7-covariate model. This reduced model yields lower complexity and more interpretability while sustaining an adjusted R2 of 0.626, compared to the full model’s adjusted R2 of 0.663. A reduced generalized additive model (GAM) with interaction terms drawn from the linear model variable selection demonstrated an adjusted R2 of 0.695, indicating a better fit that comes at the cost of reduced interpretability and higher computational requirements than the linear models. The goal of this work is to disentangle environmental indicators of post-fire evapotranspiration change, such that predictive modeling of future wildfire impacts on evapotranspiration can be achieved.


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      Last Updated Nov 22, 2024 Related Terms
      General Explore More
      8 min read SARP East 2024 Ocean Remote Sensing Group
      Article 21 mins ago 10 min read SARP East 2024 Atmospheric Science Group
      Article 21 mins ago 11 min read SARP East 2024 Terrestrial Fluxes Group
      Article 22 mins ago View the full article
    • By NASA
      11 min read
      Preparations for Next Moonwalk Simulations Underway (and Underwater)
      Return to 2024 SARP Closeout Faculty Advisors:
      Dr. Lisa Haber, Virginia Commonwealth University
      Dr. Brandon Alveshere, Virginia Commonwealth University
      Dr. Chris Gough, Virginia Commonwealth University
      Graduate Mentor:
      Mindy Priddy, Virginia Commonwealth University

      Mindy Priddy, Graduate Mentor
      Mindy Priddy, graduate mentor for the 2024 SARP Terrestrial Fluxes group, provides an introduction for each of the group members and shares behind-the scenes moments from the internship.

      Angelina De La Torre
      Using NDVI as a Proxy for GPP to Predict Carbon Dioxide Fluxes
      Angelina De La Torre
      Climate change, driven primarily by greenhouse gases, poses a threat to the future of our planet. Among these gases is carbon dioxide (CO₂), which has a much longer atmospheric residence time compared to other greenhouse gases. One potential factor in reducing atmospheric CO₂ enrichment is plant productivity. Gross Primary Productivity (GPP) estimates the amount of CO₂ fixed during photosynthesis. The Normalized Difference Vegetation Index (NDVI) provides insight into the health of an ecosystem by measuring the density and greenness of vegetation. Therefore, it can be inferred that there is a relationship between NDVI and GPP, as greener plants are likely more productive. In this study, we used NDVI as a proxy for GPP and analyzed the effect NDVI had on CO₂ fluxes during California’s wet season between January and March 2023 in a restored tidal freshwater wetland. GPP and CO₂ flux data were obtained from the Dutch Slough AmeriFlux tower in Oakley, California. Landsat data were used to calculate the average NDVI. The influence of NDVI on GPP was assessed using linear regression. A second linear regression was then performed using NDVI and CO₂ flux, of which GPP is one component. We anticipate that wetlands with greater vegetation density will have lower CO₂ emissions.

      Because Landsat data scans in 16-day intervals, daily variation in NDVI could not be observed. This translates to a frequency discrepancy between the Landsat and AmeriFlux data, as AmeriFlux towers measure in half-hour intervals. Additionally, the wet season represented was limited by data availability, as the data before 2023 were unavailable. Despite data limitations in this study, the outlined process could be repeated in various wetland and climate classifications for further analysis of a larger sample size. This study could assist in developing strategies to increase CO₂ sequestration in an attempt to slow the effects of climate change.

      Samarth Jayadev
      Using Machine Learning to Assess Relationships between NDVI and Net Carbon Exchange During the COVID-19 Pandemic
      Samarth Jayadev
      Understanding the movement of carbon between Earth’s land surface and atmosphere is essential for ecosystem monitoring, creating climate change mitigation strategies, and assessing the carbon budget on national to global scales. Measures of greenness serve as indicators of processes such as photosynthesis that control carbon exchange and are vital in modeling of carbon fluxes. NASA’s Orbiting Carbon Observatory (OCO-2) provides high quality measurements of column-averaged CO₂ concentrations that can be used to derive net carbon exchange (NCE), a measure of CO₂ flux between terrestrial ecosystems and the atmosphere.
      From OCO-2, NCE data collected at the land nadir, land glint satellite position combined with in situ sampling can provide accurate measurements on a 1°x1° scale suitable for carbon flux characterization across the contiguous United States (CONUS). Normalized difference vegetation index (NDVI), which ranges from -1 to +1, measures the greenness of vegetation, serving as an indicator of plant density and health. This can help to understand ecosystem to carbon-cycle interactions and be leveraged for determining patterns with NCE. We examined the relationship between NDVI and NCE across CONUS during 2020 using Gradient Boosting Decision Trees (GBDT) which specialize in classifying and predicting non-linear relationships. This algorithm takes multiple weak learners (decision trees) and combines their predictions in an iterative ensemble method to improve prediction accuracy. Feature and permutation importance tests found that January and August (trough and peak NDVI, respectively) were the highest weighted predictor variables related to NCE. The dataset was split in a 90% training 10% test ratio across latitude/longitude grid cells to assess and verify model performance. Using the mean squared error loss function and hyperparameters with optimal estimators, tree depth, sample split, and learning rate the algorithm was able to converge the test predictions to match the deviance of the training data. The gradient boosting model can be applied to different months and years of NDVI/NCE to further explore these relationships or a multitude of research questions. Further studies should consider integrating land use and land cover change variables such as bare land and urbanization to improve predictions of NCE.

      Makai Ogoshi
      Deep-learning Derived Spaceborne Canopy Structural Metrics Predict Forest Carbon Fluxes
      Makai Ogoshi
      Terrestrial and airborne lidar data products describing canopy structure are potent predictors of forest carbon fluxes, but whether satellite data products produce similarly robust indicators of canopy structure is not known. The assessment of contemporary spaceborne lidar and other remote sensing data products as predictors of carbon fluxes is crucial to next generation instrument and data product design and large-spatial scale modeling. We investigated relationships between deciduous broadleaf forest canopy structure, derived from deep-learning models created with lidar data from GEDI and optical imagery from Sentinel-2, and forest carbon exchange. These included comparisons to in-situ continuous net ecosystem exchange (NEE), gross primary production (GPP), and net primary production (NPP). We find that the mean  canopy height from the gridded spaceborne product has a strong correlation with forest NPP, similar to prior analysis with ground-based lidar (portable canopy lidar; PCL). For comparison to NPP, heights taken from the gridded spaceborne product were compared by overlapping the product with nine terrestrial forest sites from the National Ecological Observatory Network (NEON). We used standard deviation of canopy height as a measure of canopy structural complexity. Complexity derived from the gridded spaceborne product does not show the same strong correlation with NPP as found when using PCL. Mean annual GPP and NEE across five years were compared to the gridded spaceborne product at six Fluxnet2015-tower sites with continuous, gap-filled carbon flux data. When compared to in-situ flux tower data, neither mean canopy height nor structural complexity strongly correlate to annual NEE or GPP. Primarily, the finding that derived spaceborne products exhibit a strong correlation between forest canopy height and NPP will advance global-scale application of forest-carbon flux predictions. Secondarily, a variety of limitations highlight shortcomings in the current terrestrial flux data network. A small number of available study sites, both spatially and temporally, and lack of resolution in vertical complexity of canopy structure both contribute to uncertainty in assessing the relationships to NEE and GPP.

      Sebastian Reed
      Porewater Methane Concentrations Vary Significantly Across A Freshwater Tidal Wetland
      Sebastian Reed
      Methane is a potent greenhouse gas that is over 80 times more powerful than CO₂ at trapping heat and accounts for an estimated 30% of global temperature rise associated with climate change. The largest natural source of methane worldwide is wetlands. Despite the role of methane in driving climate change, the magnitude of global annual wetland methane flux remains highly uncertain. This study analyzes the effects of greenness (assessed using Normalized Difference Vegetation Index; NDVI), plant species composition, rooting depth, atmospheric methane concentration, and plant longevity on porewater methane concentration at the Kimages Rice Rivers Center tidal freshwater wetland. Samples for atmospheric and porewater concentrations were conducted in situ in June 2024. For each sampling location (n = 23) we collected whole air samples (WAS) 2m above the marsh surface and porewater samples 5cm below the marsh surface. We visually assessed species composition at each sample location, with 12 species of wetland plants present overall. We used the TRY plant database to find the rooting depth, leaf nitrogen content, and lifespan of each species. Drone multispectral data from 2023 was used to estimate NDVI values. These variables were compared to the pore water methane concentration via stepwise linear regression. Leaf N content, NDVI, plant species, and WAS sampling did not show statistically significant correlation to porewater methane concentration. Rooting depth showed a slight positive correlation with porewater methane (alpha = 0.1, p = 0.08, R^2 = 0.1). Samples with only perennial plants (as opposed to annual plants) had a higher mean value of porewater methane (p = 0.1). Analyzing porewater methane provides insight as to what wetland components affect methanogenesis and methane release, which aids in assessing which plant functional traits are most responsible for driving or mitigating climate change. Results from this study and future research in this area has the potential to more accurately assess how methane cycles through wetlands to the atmosphere.

      Nohemi Rodarte
      Understanding the vertical profile of CO₂ concentration: How carbon dioxide levels change with altitude
      Nohemi Rodarte
      Carbon dioxide (CO₂) is one of the main greenhouse gasses that contribute to global warming.While the relationship between CO₂ concentrations and land cover types, such as forests and urban areas, is well documented, there is limited knowledge of how CO₂ concentrations vary with altitude at fine spatial scales. Guided by our hypothesis that CO₂ levels vary with altitude and increase with elevation, we used airborne data collected from the B200 aircraft, which flew at different altitudes (400 to 1200 feet) above the urban area of Hopewell, Virginia, between 9:40 AM and 10:40 AM. We analyzed the CO₂ concentrations recorded by the flight to obtain the median and range for each 100 feet of altitude. Our results reveal that carbon dioxide concentrations varied significantly across the range of altitudes investigated. Within the area studied, CO₂ concentrations were found to range between 410 and 470 ppm. The distribution of these concentrations along the altitude gradient shows a bimodal pattern, with notable peaks at altitudes of 700 to 800 feet and 1100 to 1200 feet. Although CO₂ levels were present at all measured altitudes, there was a noticeable drop in the mean concentration at 800 feet,which then stabilized until reaching 1,000 feet before rising again. This pattern indicates that the concentrations of this greenhouse gas are not uniformly distributed with altitude, but rather vary significantly, showing higher concentrations at certain elevations and lower concentrations at others. The CO₂ distribution fluctuates with altitude, showing higher or lower levels at specific heights rather than a smooth gradient, indicating that altitude impacts CO₂ concentrations. While we did not identify the drivers of this change, future studies could evaluate how factors such as surface emissions, atmospheric mixing, and local conditions may contribute to vertical CO₂ profiles, since the altitudes we considered in this research are within the troposphere.

      Camille Shaw
      Linking NDVI with CO₂ and CH₄ Fluxes: Insights into Vegetation and Urban Source-Sink Dynamics in the Great Dismal Swamp
      Camille Shaw
      In recent years, carbon dioxide, methane, and other greenhouse gases have gained attention because of their contribution to the rise in Earth’s global mean temperature. Methane and carbon dioxide have various sources and sinks, but an expanding array of sources have created a need to assess ongoing change in carbon balance. This study aims to quantify the relationship between Normalized Difference Vegetation Index, or NDVI, and methane and carbon dioxide fluxes. We measured carbon dioxide and methane concentrations within the boundary layer using the PICARRO instrument, focusing on the Great Dismal Swamp, a forested wetland, and surrounding areas in the Eastern Mid-Atlantic Region. Data collection occurred at various times of day and along different flight paths in 2016, 2017, and 2024, with each year representing data from a single season, either spring or fall, for temporal analysis. We calculated methane and carbon dioxide fluxes along the flight paths using airborne eddy covariance, a method for capturing accurate flux measurements while accounting for the mixing of gases in the boundary layer caused by heat. Additionally, we calculated NDVI for this area using NASA’s Landsat 8 and 9 satellite imagery. Analysis of the afternoon flight data revealed a negative linear correlation between NDVI and carbon dioxide flux. Urban areas, characterized by low NDVI, exhibit a positive carbon dioxide flux as a consequence of emissions from vehicles, while forested areas, with high NDVI, show a negative carbon dioxide flux because of photosynthesis. In contrast, methane flux shows minimal correlation with NDVI. The lack of correlation arises because forested wetlands, with high NDVI, emit substantial amounts of methane, while urban areas, despite having low NDVI, still produce significant methane emissions from landfills and industrial activities. Future research could further investigate how seasonal and diurnal variations influence the correlations between NDVI and greenhouse gases by collecting comprehensive data across all seasons within a given year and at various times of the day.

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