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      in Energy

      Radio-frequency wave scattering improves fusion simulations

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      In the quest for fusion energy, understanding how radio-frequency (RF) waves travel (or “propagate”) in the turbulent interior of a fusion furnace is crucial to maintaining an efficient, continuously operating power plant. Transmitted by an antenna in the doughnut-shaped vacuum chamber common to magnetic confinement fusion devices called tokamaks, RF waves heat the plasma fuel and drive its current around the toroidal interior. The efficiency of this process can be affected by how the wave’s trajectory is altered (or “scattered”) by conditions within the chamber.

      Researchers have tried to study these RF processes using computer simulations to match the experimental conditions. A good match would validate the computer model, and raise confidence in using it to explore new physics and design future RF antennas that perform efficiently. While the simulations can accurately calculate how much total current is driven by RF waves, they do a poor job at predicting where exactly in the plasma this current is produced.

      Now, in a paper published in the Journal of Plasma Physics, MIT researchers suggest that the models for RF wave propagation used for these simulations have not properly taken into account the way these waves are scattered as they encounter dense, turbulent filaments present in the edge of the plasma known as the “scrape-off layer” (SOL).

      Bodhi Biswas, a graduate student at the Plasma Science and Fusion Center (PSFC) under the direction of Senior Research Scientist Paul Bonoli, School of Engineering Distinguished Professor of Engineering Anne White, and Principal Research Scientist Abhay Ram, who is the paper’s lead author. Ram compares the scattering that occurs in this situation to a wave of water hitting a lily pad: “The wave crashing with the lily pad will excite a secondary, scattered wave that makes circular ripples traveling outward from the plant. The incoming wave has transferred energy to the scattered wave. Some of this energy is reflected backwards (in relation to the incoming wave), some travels forwards, and some is deflected to the side. The specifics all depend on the particular attributes of the wave, the water, and the lily pad. In our case, the lily pad is the plasma filament.”

      Until now, researchers have not properly taken these filaments and the scattering they provoke into consideration when modeling the turbulence inside a tokamak, leading to an underestimation of wave scattering. Using data from PSFC tokamak Alcator C-Mod, Biswas shows that using the new method of modeling RF-wave scattering from SOL turbulence provides results considerably different from older models, and a much better match to experiments. Notably, the “lower-hybrid” wave spectrum, crucial to driving plasma current in a steady-state tokamak, appears to scatter asymmetrically, an important effect not accounted for in previous models.

      Biswas’s advisor Paul Bonoli is well acquainted with traditional “ray-tracing” models, which evaluate a wave trajectory by dividing it into a series of rays. He has used this model, with its limitations, for decades in his own research to understand plasma behavior. Bonoli says he is pleased that “the research results in Bodhi’s doctoral thesis have refocused attention on the profound effect that edge turbulence can have on the propagation and absorption of radio-frequency power.”

      Although ray-tracing treatments of scattering do not fully capture all the wave physics, a “full-wave” model that does would be prohibitively expensive. To solve the problem economically, Biswas splits his analysis into two parts: (1) using ray tracing to model the trajectory of the wave in the tokamak assuming no turbulence, while (2) modifying this ray-trajectory with the new scattering model that accounts for the turbulent plasma filaments.

      “This scattering model is a full-wave model, but computed over a small region and in a simplified geometry so that it is very quick to do,” says Biswas. “The result is a ray-tracing model that, for the first time, accounts for full-wave scattering physics.”

      Biswas notes that this model bridges the gap between simple scattering models that fail to match experiment and full-wave models that are prohibitively expensive, providing reasonable accuracy at low cost.

      “Our results suggest scattering is an important effect, and that it must be taken into account when designing future RF antennas. The low cost of our scattering model makes this very doable.”

      “This is exciting progress,” says Syun’ichi Shiraiwa, staff research physicist at the Princeton Plasma Physics Laboratory. “I believe that Bodhi’s work provides a clear path to the end of a long tunnel we have been in. His work not only demonstrates that the wave scattering, once accurately accounted for, can explain the experimental results, but also answers a puzzling question: why previous scattering models were incomplete, and their results unsatisfying.”

      Work is now underway to apply this model to more plasmas from Alcator C-Mod and other tokamaks. Biswas believes that this new model will be particularly applicable to high-density tokamak plasmas, for which the standard ray-tracing model has been noticeably inaccurate. He is also excited that the model could be validated by DIII-D National Fusion Facility, a fusion experiment on which the PSFC collaborates.

      “The DIII-D tokamak will soon be capable of launching lower hybrid waves and measuring its electric field in the scrape-off layer. These measurements could provide direct evidence of the asymmetric scattering effect predicted by our model.” More

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      in Environment

      Scientists project increased risk to water supplies in South Africa this century

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      In 2018, Cape Town, South Africa’s second most populous city, came very close to running out of water as the multi-year “Day Zero” drought depleted its reservoirs. Since then, researchers from Stanford University determined that climate change had made this extreme drought five to six times more likely, and warned that a lot more Day Zero events could occur in regions with similar climates in the future. A better understanding of likely surface air temperature and precipitation trends in South Africa and other dry, populated areas around the world in the coming decades could empower decision-makers to pursue science-based climate mitigation and adaptation measures designed to reduce the risk of future Day Zero events.    

      Toward that end, researchers at the MIT Joint Program on the Science and Policy of Global Change, International Food Policy Research Institute, and CGIAR have produced modeled projections of 21st-century changes in seasonal surface air temperature and precipitation for South Africa that systematically and comprehensively account for uncertainties in how Earth and socioeconomic systems behave and co-evolve. Presented in a study in the journal Climatic Change, these projections show how temperature and precipitation over three sub-national regions — western, central, and eastern South Africa — are likely to change under a wide range of global climate mitigation policy scenarios.

      In a business-as-usual global climate policy scenario in which no emissions or climate targets are set or met, the projections show that for all three regions, there’s a greater-than 50 percent likelihood that mid-century temperatures will increase threefold over the current climate’s range of variability. But the risk of these mid-century temperature increases is effectively eliminated through more aggressive climate targets.

      The business-as-usual projections indicate that the risk of decreased precipitation levels in western and central South Africa is three to four times higher than the risk of increased precipitation levels. Under a global climate mitigation policy designed to cap global warming at 1.5 degrees Celsius by 2100, the risk of precipitation changes within South Africa toward the end of the century (2065-74) is similar to the risk during the 2030s in the business-as-usual scenario.

      Rising risks of substantially reduced precipitation levels throughout this century under a business-as-usual scenario suggest increased reliance and stress on the widespread water-efficiency measures established in the aftermath of the Day Zero drought. But a 1.5 C global climate mitigation policy would delay these risks by 30 years, giving South Africa ample lead time to prepare for and adapt to them.

      “Our analysis provides risk-based evidence on the benefits of climate mitigation policies as well as unavoidable climate impacts that will need to be addressed through adaptive measures,” says MIT Joint Program Deputy Director C. Adam Schlosser, the lead author of the study. “Global action to limit human-induced warming could give South Africa enough time to secure sufficient water supplies to sustain its population. Otherwise, anticipated climate shifts by the middle of the next decade may well make Day-Zero situations more common.”

      This study is part of an ongoing effort to assess the risks that climate change poses for South Africa’s agricultural, economic, energy and infrastructure sectors. More

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      in Environment

      MIT collaborates with Biogen on three-year, $7 million initiative to address climate, health, and equity

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      MIT and Biogen have announced that they will collaborate with the goal to accelerate the science and action on climate change to improve human health. This collaboration is supported by a three-year, $7 million commitment from the company and the Biogen Foundation. The biotechnology company, headquartered in Cambridge, Massachusetts’ Kendall Square, discovers and develops therapies for people living with serious neurological diseases.

      “We have long believed it is imperative for Biogen to make the fight against climate change central to our long-term corporate responsibility commitments. Through this collaboration with MIT, we aim to identify and share innovative climate solutions that will deliver co-benefits for both health and equity,” says Michel Vounatsos, CEO of Biogen. “We are also proud to support the MIT Museum, which promises to make world-class science and education accessible to all, and honor Biogen co-founder Phillip A. Sharp with a dedication inside the museum that recognizes his contributions to its development.”

      Biogen and the Biogen Foundation are supporting research and programs across a range of areas at MIT.

      Advancing climate, health, and equity

      The first such effort involves new work within the MIT Joint Program on the Science and Policy of Global Change to establish a state-of-the-art integrated model of climate and health aimed at identifying targets that deliver climate and health co-benefits.

      “Evidence suggests that not all climate-related actions deliver equal health benefits, yet policymakers, planners, and stakeholders traditionally lack the tools to consider how decisions in one arena impact the other,” says C. Adam Schlosser, deputy director of the MIT Joint Program. “Biogen’s collaboration with the MIT Joint Program — and its support of a new distinguished Biogen Fellow who will develop the new climate/health model — will accelerate our efforts to provide decision-makers with these tools.”

      Biogen is also supporting the MIT Technology and Policy Program’s Research to Policy Engagement Initiative to infuse human health as a key new consideration in decision-making on the best pathways forward to address the global climate crisis, and bridge the knowledge-to-action gap by connecting policymakers, researchers, and diverse stakeholders. As part of this work, Biogen is underwriting a distinguished Biogen Fellow to advance new research on climate, health, and equity.

      “Our work with Biogen has allowed us to make progress on key questions that matter to human health and well-being under climate change,” says Noelle Eckley Selin, who directs the MIT Technology and Policy Program and is a professor in the MIT Institute for Data, Systems, and Society and the Department of Earth, Atmospheric and Planetary Sciences. “Further, their support of the Research to Policy Engagement Initiative helps all of our research become more effective in making change.”

      In addition, Biogen has joined 13 other companies in the MIT Climate and Sustainability Consortium (MCSC), which is supporting faculty and student research and developing impact pathways that present a range of actionable steps that companies can take — within and across industries — to advance progress toward climate targets.

      “Biogen joining the MIT Climate and Sustainability Consortium represents our commitment to working with member companies across a diverse range of industries, an approach that aims to drive changes swift and broad enough to match the scale of the climate challenge,” says Jeremy Gregory, executive director of the MCSC. “We are excited to welcome a member from the biotechnology space and look forward to harnessing Biogen’s perspectives as we continue to collaborate and work together with the MIT community in exciting and meaningful ways.”

      Making world-class science and education available to MIT Museum visitors

      Support from Biogen will honor Nobel laureate, MIT Institute professor, and Biogen co-founder Phillip A. Sharp with a named space inside the new Kendall Square location of the MIT Museum, set to open in spring 2022. Biogen also is supporting one of the museum’s opening exhibitions, “Essential MIT,” with a section focused on solving real-world problems such as climate change. It is also providing programmatic support for the museum’s Life Sciences Maker Engagement Program.

      “Phil has provided fantastic support to the MIT Museum for more than a decade as an advisory board member and now as board chair, and he has been deeply involved in plans for the new museum at Kendall Square,” says John Durant, the Mark R. Epstein (Class of 1963) Director of the museum. “Seeing his name on the wall will be a constant reminder of his key role in this development, as well as a mark of our gratitude.”

      Inspiring and empowering the next generation of scientists

      Biogen funding is also being directed to engage the next generation of scientists through support for the Biogen-MIT Biotech in Action: Virtual Lab, a program designed to foster a love of science among diverse and under-served student populations.

      Biogen’s support is part of its Healthy Climate, Healthy Lives initiative, a $250 million, 20-year commitment to eliminate fossil fuels across its operations and collaborate with renowned institutions to advance the science of climate and health and support under-served communities. Additional support is provided by the Biogen Foundation to further its long-standing focus on providing students with equitable access to outstanding science education. More

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      in Energy

      MIT Energy Initiative awards seven Seed Fund grants for early-stage energy research

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      The MIT Energy Initiative (MITEI) has awarded seven Seed Fund grants to support novel, early-stage energy research by faculty and researchers at MIT. The awardees hail from a range of disciplines, but all strive to bring their backgrounds and expertise to address the global climate crisis by improving the efficiency, scalability, and adoption of clean energy technologies.

      “Solving climate change is truly an interdisciplinary challenge,” says MITEI Director Robert C. Armstrong. “The Seed Fund grants foster collaboration and innovation from across all five of MIT’s schools and one college, encouraging an ‘all hands on deck approach’ to developing the energy solutions that will prove critical in combatting this global crisis.”

      This year, MITEI’s Seed Fund grant program received 70 proposals from 86 different principal investigators (PIs) across 25 departments, labs, and centers. Of these proposals, 31 involved collaborations between two or more PIs, including 24 that involved multiple departments.

      The winning projects reflect this collaborative nature with topics addressing the optimization of low-energy thermal cooling in buildings; the design of safe, robust, and resilient distributed power systems; and how to design and site wind farms with consideration of wind resource uncertainty due to climate change.

      Increasing public support for low-carbon technologies

      One winning team aims to leverage work done in the behavioral sciences to motivate sustainable behaviors and promote the adoption of clean energy technologies.

      “Objections to scalable low-carbon technologies such as nuclear energy and carbon sequestration have made it difficult to adopt these technologies and reduce greenhouse gas emissions,” says Howard Herzog, a senior research scientist at MITEI and co-PI. “These objections tend to neglect the sheer scale of energy generation required and the inability to meet this demand solely with other renewable energy technologies.”

      This interdisciplinary team — which includes researchers from MITEI, the Department of Nuclear Science and Engineering, and the MIT Sloan School of Management — plans to convene industry professionals and academics, as well as behavioral scientists, to identify common objections, design messaging to overcome them, and prove that these messaging campaigns have long-lasting impacts on attitudes toward scalable low-carbon technologies.

      “Our aim is to provide a foundation for shifting the public and policymakers’ views about these low-carbon technologies from something they, at best, tolerate, to something they actually welcome,” says co-PI David Rand, the Erwin H. Schell Professor and professor of management science and brain and cognitive sciences at MIT Sloan School of Management.

      Siting and designing wind farms

      Michael Howland, an assistant professor of civil and environmental engineering, will use his Seed Fund grant to develop a foundational methodology for wind farm siting and design that accounts for the uncertainty of wind resources resulting from climate change.

      “The optimal wind farm design and its resulting cost of energy is inherently dependent on the wind resource at the location of the farm,” says Howland. “But wind farms are currently sited and designed based on short-term climate records that do not account for the future effects of climate change on wind patterns.”

      Wind farms are capital-intensive infrastructure that cannot be relocated and often have lifespans exceeding 20 years — all of which make it especially important that developers choose the right locations and designs based not only on wind patterns in the historical climate record, but also based on future predictions. The new siting and design methodology has the potential to replace current industry standards to enable a more accurate risk analysis of wind farm development and energy grid expansion under climate change-driven energy resource uncertainty.

      Membraneless electrolyzers for hydrogen production

      Producing hydrogen from renewable energy-powered water electrolyzers is central to realizing a sustainable and low-carbon hydrogen economy, says Kripa Varanasi, a professor of mechanical engineering and a Seed Fund award recipient. The idea of using hydrogen as a fuel has existed for decades, but it has yet to be widely realized at a considerable scale. Varanasi hopes to change that with his Seed Fund grant.

      “The critical economic hurdle for successful electrolyzers to overcome is the minimization of the capital costs associated with their deployment,” says Varanasi. “So, an immediate task at hand to enable electrochemical hydrogen production at scale will be to maximize the effectiveness of the most mature, least complex, and least expensive water electrolyzer technologies.”

      To do this, he aims to combine the advantages of existing low-temperature alkaline electrolyzer designs with a novel membraneless electrolyzer technology that harnesses a gas management system architecture to minimize complexity and costs, while also improving efficiency. Varanasi hopes his project will demonstrate scalable concepts for cost-effective electrolyzer technology design to help realize a decarbonized hydrogen economy.

      Since its establishment in 2008, the MITEI Seed Fund Program has supported 194 energy-focused seed projects through grants totaling more than $26 million. This funding comes primarily from MITEI’s founding and sustaining members, supplemented by gifts from generous donors.

      Recipients of the 2021 MITEI Seed Fund grants are:

      “Design automation of safe, robust, and resilient distributed power systems” — Chuchu Fan of the Department of Aeronautics and Astronautics
      “Advanced MHD topping cycles: For fission, fusion, solar power plants” — Jeffrey Freidberg of the Department of Nuclear Science and Engineering and Dennis Whyte of the Plasma Science and Fusion Center
      “Robust wind farm siting and design under climate-change‐driven wind resource uncertainty” — Michael Howland of the Department of Civil and Environmental Engineering
      “Low-energy thermal comfort for buildings in the Global South: Optimal design of integrated structural-thermal systems” — Leslie Norford of the Department of Architecture and Caitlin Mueller of the departments of Architecture and Civil and Environmental Engineering
      “New low-cost, high energy-density boron-based redox electrolytes for nonaqueous flow batteries” — Alexander Radosevich of the Department of Chemistry
      “Increasing public support for scalable low-carbon energy technologies using behavorial science insights” — David Rand of the MIT Sloan School of Management, Koroush Shirvan of the Department of Nuclear Science and Engineering, Howard Herzog of the MIT Energy Initiative, and Jacopo Buongiorno of the Department of Nuclear Science and Engineering
      “Membraneless electrolyzers for efficient hydrogen production using nanoengineered 3D gas capture electrode architectures” — Kripa Varanasi of the Department of Mechanical Engineering More

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      in Security

      How diet affects tumors

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      In recent years, there has been some evidence that dietary interventions can help to slow the growth of tumors. A new study from MIT, which analyzed two different diets in mice, reveals how those diets affect cancer cells, and offers an explanation for why restricting calories may slow tumor growth.

      The study examined the effects of a calorically restricted diet and a ketogenic diet in mice with pancreatic tumors. While both of these diets reduce the amount of sugar available to tumors, the researchers found that only the calorically restricted diet reduced the availability of fatty acids, and this was linked to a slowdown in tumor growth.

      The findings do not suggest that cancer patients should try to follow either of these diets, the researchers say. Instead, they believe the findings warrant further study to determine how dietary interventions might be combined with existing or emerging drugs to help patients with cancer.

      “There’s a lot of evidence that diet can affect how fast your cancer progresses, but this is not a cure,” says Matthew Vander Heiden, director of MIT’s Koch Institute for Integrative Cancer Research and the senior author of the study. “While the findings are provocative, further study is needed, and individual patients should talk to their doctor about the right dietary interventions for their cancer.”

      MIT postdoc Evan Lien is the lead author of the paper, which appears today in Nature.

      Metabolic mechanism

      Vander Heiden, who is also a medical oncologist at Dana-Farber Cancer Institute, says his patients often ask him about the potential benefits of various diets, but there is not enough scientific evidence available to offer any definitive advice. Many of the dietary questions that patients have focus on either a calorie-restricted diet, which reduces calorie consumption by 25 to 50 percent, or a ketogenic diet, which is low in carbohydrates and high in fat and protein.

      Previous studies have suggested that a calorically restricted diet might slow tumor growth in some contexts, and such a diet has been shown to extend lifespan in mice and many other animal species. A smaller number of studies exploring the effects of a ketogenic diet on cancer have produced inconclusive results.

      “A lot of the advice or cultural fads that are out there aren’t necessarily always based on very good science,” Lien says. “It seemed like there was an opportunity, especially with our understanding of cancer metabolism having evolved so much over the past 10 years or so, that we could take some of the biochemical principles that we’ve learned and apply those concepts to understanding this complex question.”

      Cancer cells consume a great deal of glucose, so some scientists had hypothesized that either the ketogenic diet or calorie restriction might slow tumor growth by reducing the amount of glucose available. However, the MIT team’s initial experiments in mice with pancreatic tumors showed that calorie restriction has a much greater effect on tumor growth than the ketogenic diet, so the researchers suspected that glucose levels were not playing a major role in the slowdown.

      To dig deeper into the mechanism, the researchers analyzed tumor growth and nutrient concentration in mice with pancreatic tumors, which were fed either a normal, ketogenic, or calorie-restricted diet. In both the ketogenic and calorie-restricted mice, glucose levels went down. In the calorie-restricted mice, lipid levels also went down, but in mice on the ketogenic diet, they went up.

      Lipid shortages impair tumor growth because cancer cells need lipids to construct their cell membranes. Normally, when lipids aren’t available in a tissue, cells can make their own. As part of this process, they need to maintain the right balance of saturated and unsaturated fatty acids, which requires an enzyme called stearoyl-CoA desaturase (SCD). This enzyme is responsible for converting saturated fatty acids into unsaturated fatty acids.

      Both calorie-restricted and ketogenic diets reduce SCD activity, but mice on the ketogenic diet had lipids available to them from their diet, so they didn’t need to use SCD. Mice on the calorie-restricted diet, however, couldn’t get fatty acids from their diet or produce their own. In these mice, tumor growth slowed significantly, compared to mice on the ketogenic diet.

      “Not only does caloric restriction starve tumors of lipids, it also impairs the process that allows them to adapt to it. That combination is really contributing to the inhibition of tumor growth,” Lien says.

      Dietary effects

      In addition to their mouse research, the researchers also looked at some human data. Working with Brian Wolpin, an oncologist at Dana-Farber Cancer Institute and an author of the paper, the team obtained data from a large cohort study that allowed them to analyze the relationship between dietary patterns and survival times in pancreatic cancer patients. From that study, the researchers found that the type of fat consumed appears to influence how patients on a low-sugar diet fare after a pancreatic cancer diagnosis, although the data are not complete enough to draw any conclusions about the effect of diet, the researchers say.

      Although this study showed that calorie restriction has beneficial effects in mice, the researchers say they do not recommend that cancer patients follow a calorie-restricted diet, which is difficult to maintain and can have harmful side effects. However, they believe that cancer cells’ dependence on the availability of unsaturated fatty acids could be exploited to develop drugs that might help slow tumor growth.

      One possible therapeutic strategy could be inhibition of the SCD enzyme, which would cut off tumor cells’ ability to produce unsaturated fatty acids.

      “The purpose of these studies isn’t necessarily to recommend a diet, but it’s to really understand the underlying biology,” Lien says. “They provide some sense of the mechanisms of how these diets work, and that can lead to rational ideas on how we might mimic those situations for cancer therapy.”

      The researchers now plan to study how diets with a variety of fat sources — including plant or animal-based fats with defined differences in saturated, monounsaturated, and polyunsaturated fatty acid content — alter tumor fatty acid metabolism and the ratio of unsaturated to saturated fatty acids.

      The research was funded by the Damon Runyon Cancer Research Foundation, the National Institutes of Health, the Lustgarten Foundation, the Dana-Farber Cancer Institute Hale Family Center for Pancreatic Cancer Research, Stand Up to Cancer, the Pancreatic Cancer Action Network, the Noble Effort Fund, the Wexler Family Fund, Promises for Purple, the Bob Parsons Fund, the Emerald Foundation, the Howard Hughes Medical Institute, the MIT Center for Precision Cancer Medicine, and the Ludwig Center at MIT. More

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      in Security

      Rover images confirm Jezero crater is an ancient Martian lake

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      The first scientific analysis of images taken by NASA’s Perseverance rover has now confirmed that Mars’ Jezero crater — which today is a dry, wind-eroded depression — was once a quiet lake, fed steadily by a small river some 3.7 billion years ago.

      The images also reveal evidence that the crater endured flash floods. This flooding was energetic enough to sweep up large boulders from tens of miles upstream and deposit them into the lakebed, where the massive rocks lie today.

      The new analysis, published today in the journal Science, is based on images of the outcropping rocks inside the crater on its western side. Satellites had previously shown that this outcrop, seen from above, resembled river deltas on Earth, where layers of sediment are deposited in the shape of a fan as the river feeds into a lake.

      Perseverance’s new images, taken from inside the crater, confirm that this outcrop was indeed a river delta. Based on the sedimentary layers in the outcrop, it appears that the river delta fed into a lake that was calm for much of its existence, until a dramatic shift in climate triggered episodic flooding at or toward the end of the lake’s history.

      “If you look at these images, you’re basically staring at this epic desert landscape. It’s the most forlorn place you could ever visit,” says Benjamin Weiss, professor of planetary sciences in MIT’s Department of Earth, Atmospheric and Planetary Sciences and a member of the analysis team. “There’s not a drop of water anywhere, and yet, here we have evidence of a very different past. Something very profound happened in the planet’s history.”

      As the rover explores the crater, scientists hope to uncover more clues to its climatic evolution. Now that they have confirmed the crater was once a lake environment, they believe its sediments could hold traces of ancient aqueous life. In its mission going forward, Perseverance will look for locations to collect and preserve sediments. These samples will eventually be returned to Earth, where scientists can probe them for Martian biosignatures.

      “We now have the opportunity to look for fossils,” says team member Tanja Bosak, associate professor of geobiology at MIT. “It will take some time to get to the rocks that we really hope to sample for signs of life. So, it’s a marathon, with a lot of potential.”

      Tilted beds

      On Feb. 18, 2021, the Perseverance rover landed on the floor of Jezero crater, a little more than a mile away from its western fan-shaped outcrop. In the first three months, the vehicle remained stationary as NASA engineers performed remote checks of the rover’s many instruments.

      During this time, two of Perseverance’s cameras, Mastcam-Z and the SuperCam Remote Micro-Imager (RMI), captured images of their surroundings, including long-distance photos of the outcrop’s edge and a formation known as Kodiak butte, a smaller outcop that planetary geologists surmise may have once been connected to the main fan-shaped outcrop but has since partially eroded.

      Once the rover downlinked images to Earth, NASA’s Perseverance science team processed and combined the images, and were able to observe distinct beds of sediment along Kodiak butte in surprisingly high resolution. The researchers measured each layer’s thickness, slope, and lateral extent, finding that the sediment must have been deposited by flowing water into a lake, rather than by wind, sheet-like floods, or other geologic processes.

      The rover also captured similar tilted sediment beds along the main outcrop. These images, together with those of Kodiak, confirm that the fan-shaped formation was indeed an ancient delta and that this delta fed into an ancient Martian lake.

      “Without driving anywhere, the rover was able to solve one of the big unknowns, which was that this crater was once a lake,” Weiss says. “Until we actually landed there and confirmed it was a lake, it was always a question.”

      Boulder flow

      When the researchers took a closer look at images of the main outcrop, they noticed large boulders and cobbles embedded in the youngest, topmost layers of the delta. Some boulders measured as wide as 1 meter across, and were estimated to weigh up to several tons. These massive rocks, the team concluded, must have come from outside the crater, and was likely part of bedrock located on the crater rim or else 40 or more miles upstream.

      Judging from their current location and dimensions, the team says the boulders were carried downstream and into the lakebed by a flash-flood that flowed up to 9 meters per second and moved up to 3,000 cubic meters of water per second.

      “You need energetic flood conditions to carry rocks that big and heavy,” Weiss says. “It’s a special thing that may be indicative of a fundamental change in the local hydrology or perhaps the regional climate on Mars.”

      Because the huge rocks lie in the upper layers of the delta, they represent the most recently deposited material. The boulders sit atop layers of older, much finer sediment. This stratification, the researchers say, indicates that for much of its existence, the ancient lake was filled by a gently flowing river. Fine sediments — and possibly organic material — drifted down the river, and settled into a gradual, sloping delta.

      However, the crater later experienced sudden flash floods that deposited large boulders onto the delta. Once the lake dried up, and over billions of years wind eroded the landscape, leaving the crater we see today.

      The cause of this climate turnaround is unknown, although Weiss says the delta’s boulders may hold some answers.

      “The most surprising thing that’s come out of these images is the potential opportunity to catch the time when this crater transitioned from an Earth-like habitable environment, to this desolate landscape wasteland we see now,” he says. “These boulder beds may be records of this transition, and we haven’t seen this in other places on Mars.”

      This research was supported, in part, by NASA. More

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      in Environment

      New “risk triage” platform pinpoints compounding threats to US infrastructure

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      Over a 36-hour period in August, Hurricane Henri delivered record rainfall in New York City, where an aging storm-sewer system was not built to handle the deluge, resulting in street flooding. Meanwhile, an ongoing drought in California continued to overburden aquifers and extend statewide water restrictions. As climate change amplifies the frequency and intensity of extreme events in the United States and around the world, and the populations and economies they threaten grow and change, there is a critical need to make infrastructure more resilient. But how can this be done in a timely, cost-effective way?

      An emerging discipline called multi-sector dynamics (MSD) offers a promising solution. MSD homes in on compounding risks and potential tipping points across interconnected natural and human systems. Tipping points occur when these systems can no longer sustain multiple, co-evolving stresses, such as extreme events, population growth, land degradation, drinkable water shortages, air pollution, aging infrastructure, and increased human demands. MSD researchers use observations and computer models to identify key precursory indicators of such tipping points, providing decision-makers with critical information that can be applied to mitigate risks and boost resilience in infrastructure and managed resources.

      At MIT, the Joint Program on the Science and Policy of Global Change has since 2018 been developing MSD expertise and modeling tools and using them to explore compounding risks and potential tipping points in selected regions of the United States. In a two-hour webinar on Sept. 15, MIT Joint Program researchers presented an overview of the program’s MSD research tool set and its applications.  

      MSD and the risk triage platform

      “Multi-sector dynamics explores interactions and interdependencies among human and natural systems, and how these systems may adapt, interact, and co-evolve in response to short-term shocks and long-term influences and stresses,” says MIT Joint Program Deputy Director C. Adam Schlosser, noting that such analysis can reveal and quantify potential risks that would likely evade detection in siloed investigations. “These systems can experience cascading effects or failures after crossing tipping points. The real question is not just where these tipping points are in each system, but how they manifest and interact across all systems.”

      To address that question, the program’s MSD researchers have developed the MIT Socio-Environmental Triage (MST) platform, now publicly available for the first time. Focused on the continental United States, the first version of the platform analyzes present-day risks related to water, land, climate, the economy, energy, demographics, health, and infrastructure, and where these compound to create risk hot spots. It’s essentially a screening-level visualization tool that allows users to examine risks, identify hot spots when combining risks, and make decisions about how to deploy more in-depth analysis to solve complex problems at regional and local levels. For example, MST can identify hot spots for combined flood and poverty risks in the lower Mississippi River basin, and thereby alert decision-makers as to where more concentrated flood-control resources are needed.

      Successive versions of the platform will incorporate projections based on the MIT Joint Program’s Integrated Global System Modeling (IGSM) framework of how different systems and stressors may co-evolve into the future and thereby change the risk landscape. This enhanced capability could help uncover cost-effective pathways for mitigating and adapting to a wide range of environmental and economic risks.  

      MSD applications

      Five webinar presentations explored how MIT Joint Program researchers are applying the program’s risk triage platform and other MSD modeling tools to identify potential tipping points and risks in five key domains: water quality, land use, economics and energy, health, and infrastructure. 

      Joint Program Principal Research Scientist Xiang Gao described her efforts to apply a high-resolution U.S. water-quality model to calculate a location-specific, water-quality index over more than 2,000 river basins in the country. By accounting for interactions among climate, agriculture, and socioeconomic systems, various water-quality measures can be obtained ranging from nitrate and phosphate levels to phytoplankton concentrations. This modeling approach advances a unique capability to identify potential water-quality risk hot spots for freshwater resources.

      Joint Program Research Scientist Angelo Gurgel discussed his MSD-based analysis of how climate change, population growth, changing diets, crop-yield improvements and other forces that drive land-use change at the global level may ultimately impact how land is used in the United States. Drawing upon national observational data and the IGSM framework, the analysis shows that while current U.S. land-use trends are projected to persist or intensify between now and 2050, there is no evidence of any concerning tipping points arising throughout this period.  

      MIT Joint Program Research Scientist Jennifer Morris presented several examples of how the risk triage platform can be used to combine existing U.S. datasets and the IGSM framework to assess energy and economic risks at the regional level. For example, by aggregating separate data streams on fossil-fuel employment and poverty, one can target selected counties for clean energy job training programs as the nation moves toward a low-carbon future. 

      “Our modeling and risk triage frameworks can provide pictures of current and projected future economic and energy landscapes,” says Morris. “They can also highlight interactions among different human, built, and natural systems, including compounding risks that occur in the same location.”  

      MIT Joint Program research affiliate Sebastian Eastham, a research scientist at the MIT Laboratory for Aviation and the Environment, described an MSD approach to the study of air pollution and public health. Linking the IGSM with an atmospheric chemistry model, Eastham ultimately aims to better understand where the greatest health risks are in the United States and how they may compound throughout this century under different policy scenarios. Using the risk triage tool to combine current risk metrics for air quality and poverty in a selected county based on current population and air-quality data, he showed how one can rapidly identify cardiovascular and other air-pollution-induced disease risk hot spots.

      Finally, MIT Joint Program research affiliate Alyssa McCluskey, a lecturer at the University of Colorado at Boulder, showed how the risk triage tool can be used to pinpoint potential risks to roadways, waterways, and power distribution lines from flooding, extreme temperatures, population growth, and other stressors. In addition, McCluskey described how transportation and energy infrastructure development and expansion can threaten critical wildlife habitats.

      Enabling comprehensive, location-specific analyses of risks and hot spots within and among multiple domains, the Joint Program’s MSD modeling tools can be used to inform policymaking and investment from the municipal to the global level.

      “MSD takes on the challenge of linking human, natural, and infrastructure systems in order to inform risk analysis and decision-making,” says Schlosser. “Through our risk triage platform and other MSD models, we plan to assess important interactions and tipping points, and to provide foresight that supports action toward a sustainable, resilient, and prosperous world.”

      This research is funded by the U.S. Department of Energy’s Office of Science as an ongoing project. More

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      in Environment

      The language of change

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      Ryan Conti came to MIT hoping to find a way to do good things in the world. Now a junior, his path is pointing toward a career in climate science, and he is preparing by majoring in both math and computer science and by minoring in philosophy.

      Language for catalyzing change

      Philosophy matters to Conti not only because he is interested in ethics — questions of right and wrong — but because he believes the philosophy of language can illuminate how humans communicate, including factors that contribute to miscommunication. “I care a lot about climate change, so I want to do scientific work on it, but I also want to help work on policy — which means conveying arguments well and convincing people so that change can occur,” he says.Conti says a key reason he came to MIT was because the Institute has such a strong School of Humanities, Arts, and Social Sciences (MIT SHASS). “One of the big factors in my choosing MIT is that the humanities departments here are really, really good,” says Conti, who was named a 2021 Burchard Scholar in honor of his excellence in the Institute’s humanistic fields. “I was considering literature, writing, philosophy, linguistics, all of that.”Revitalizing endangered indigenous languages

      Within MIT SHASS, Conti has focused academically on the philosophy of language, and he is also personally pursuing another linguistic passion — the preservation and revitalization of endangered indigenous languages. Raised in Plano, Texas, Conti is a citizen of the Chickasaw Nation, which today has fewer than 50 first-language speakers left.“I’ve been studying the language on my own. It’s something I really care about a lot, the entire endeavor of language revitalization,” says Conti, who credits his maternal grandmother with instilling his appreciation for his heritage. “She would always tell me that I should be proud of it,” he says. “As I got older and understood the history of things, the precarious nature of our language, I got more invested.” Conti says working to revitalize the Chickasaw language “could be one of the most important things I do with my life.”Already, MIT has given him an opportunity — through the MIT Solve initiative — to participate in a website project for speakers of Makah, an endangered indigenous language of the Pacific Northwest. “The thrust at a high level is trying to use AI [artificial intelligence] to develop speech-to-text software for languages in the Wakashan language family,” he says. The project taught him a lot about natural language processing and automatic speech recognition, he adds, although his website design was not chosen for implementation.

      Glacier dynamics, algorithms — and Quizbowl!

      MIT has also given Conti some experience on the front lines of climate change. Through the Undergraduate Research Opportunities Program, he has been working in MIT’s Glacier Dynamics and Remote Sensing Group, developing machine learning algorithms to improve iceberg detection using satellite imagery. After graduation, Conti plans to pursue a PhD in climate science, perhaps continuing to work in glaciology.He also hopes to participate in a Chickasaw program that pairs students with native speakers to become fluent. He says he sees some natural overlap between his two passions. “Issues of indigenous sovereignty and language preservation are inherently linked with climate change, because the effects of climate change fall unequally on poor communities, which are oftentimes indigenous communities,” he says.For the moment, however, those plans still lie at least two years in the future. In the meantime, Conti is having fun serving as vice president of the MIT Quizbowl Team, an academic quiz team that competes across the region and often participate in national tournaments. What are Conti’s competition specialties? Literature and philosophy. 

      Story prepared by MIT SHASS CommunicationsEditor, Designer: Emily Hiestand, Communications DirectorSenior Writer: Kathryn O’Neill, Associate News Manager More