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  • richardmitnick 9:27 am on May 22, 2020 Permalink | Reply
    Tags: "A Plate Boundary Emerges Between India and Australia", , Eos, Mid-ocean ridges reveal plate boundaries., Multibeam bathymetry, , Slip rates, Tectonic plates blanket the Earth like a patchwork quilt.   

    From Eos: “A Plate Boundary Emerges Between India and Australia” 

    From AGU
    Eos news bloc

    From Eos

    18 May 2020
    Katherine Kornei

    Mid-ocean ridges, like this one near Vancouver Island, Canada, reveal plate boundaries. Credit: Ocean Networks Canada.

    Tectonic plates blanket the Earth like a patchwork quilt.

    The tectonic plates of the world were mapped in 1996, USGS.

    Now, researchers think they’ve found a new plate boundary—a line of stitching in that tectonic quilt—in the northern Indian Ocean. This discovery, made using bathymetric and seismic data, supports the hypothesis that the India-Australia-Capricorn plate is breaking apart, the team suggests.

    Earthquakes in Unexpected Places

    In 2012, two enormous earthquakes occurred near Indonesia. But these massive temblors—magnitudes 8.6 and 8.2—weren’t associated with the region’s notorious Andaman-Sumatra subduction zone. Instead, they struck within the India-Australia-Capricorn plate, which made them unusual because most earthquakes occur at plate boundaries.

    These earthquakes “reactivated the debate” about the India-Australia-Capricorn plate, said Aurélie Coudurier-Curveur, a geoscientist at the Institute of Earth Physics of Paris.

    Some scientists have proposed that this plate, which underlies most of the Indian Ocean, is breaking apart. That’s not a wholly unexpected phenomenon because this plate is being tugged in multiple directions, said Coudurier-Curveur. Its eastern extent is sliding under the Sunda plate, but its northern portion is buckling up against the Himalayas, which are acting like a backstop.

    “There’s a velocity difference that is potentially increasing,” said Coudurier-Curveur, who completed this work while at the Earth Observatory of Singapore at Nanyang Technological University.

    Zooming in on Fractures

    Coudurier-Curveur and her colleagues studied one particularly fracture riddled region of the India-Australia-Capricorn plate near the Andaman-Sumatra subduction zone. They used seismic reflection imaging and multibeam bathymetry, which involve bouncing sound waves off sediments and measuring the returning signals, to look for structures at and below seafloor consistent with an active fault.

    Along one giant crack that the team dubbed F6a, Coudurier-Curveur and her colleagues found 60 pull-apart basins, characteristic depressions that can form along strike-slip plate boundaries. The team showed that the basins followed a long, linear track that passed near the epicenters of both of the 2012 earthquakes.

    “It’s at least 1,000 kilometers,” said Coudurier-Curveur. “It might be even longer, but we don’t have the data to show where it extends.” This feature, the team surmised, was consistent with being a plate boundary. An important next step was to estimate its slip rate.

    Slower Than San Andreas

    To do that, the scientists relied on two quantities: the length of the largest, and presumably oldest, pull-apart basin (roughly 5,800 meters) and the duration of the most recent episode of fault activity (roughly 2.3 million years). By dividing the length of the pull-apart basin by this time interval, they calculated a maximum slip rate of about 2.5 millimeters per year. That’s roughly tenfold slower than the rate along other strike-slip plate boundaries like the San Andreas Fault but not much slower than the slip rates of the Dead Sea Fault and the Owen Fracture Zone, the team noted.

    On the basis of that slip rate, Coudurier-Curveur and her collaborators estimated the return interval for an earthquake like the magnitude 8.6 one reported in April 2012. Assuming that such an event releases several tens of meters of coseismic slip, a similar earthquake might occur every 20,000 years or so, said Coudurier-Curveur. “Once you release the stress, you need a number of years to build that stress again.”

    These results were published in March in Geophysical Research Letters.

    These findings are convincing, said Kevin Kwong, a geophysicist at the University of Washington in Seattle not involved in the research. “What we see in this region in the middle of the ocean is very analogous to other plate boundary regions.”

    But continuing to monitor this part of the seafloor for earthquakes is also important, he said, because temblors illustrate plate boundaries. That work will require new instrumentation, said Kwong. “We don’t have the seismic stations nearby.”

    See the full article here .


    Please help promote STEM in your local schools.

    Stem Education Coalition

    Eos is the leading source for trustworthy news and perspectives about the Earth and space sciences and their impact. Its namesake is Eos, the Greek goddess of the dawn, who represents the light shed on understanding our planet and its environment in space by the Earth and space sciences.

  • richardmitnick 11:37 am on March 20, 2020 Permalink | Reply
    Tags: "U.S. Readies Health Response for the Next Big Eruption", , , Eos, , Mount St. Helens spawned a new field of science concerned with the health impacts of volcanoes in the short and long term., Volcano experts meet regularly to discuss eruption forecasting and hazard modeling.,   

    From Eos: “U.S. Readies Health Response for the Next Big Eruption” 

    From AGU
    Eos news bloc

    From Eos

    12 March 2020
    Kimberly M. S. Cartier

    Forty years after the explosive eruption of Mount St. Helens, scientists, communities, and civic officials are evaluating plans to best protect public health before, during, and after an eruption.

    A Plinian eruption column billows from Mount St. Helens on 18 May 1980. Credit: USGS/Robert Krimmel.

    Whakaari volcano in New Zealand erupted on 9 December 2019. Although experts had warned for weeks that the stratovolcano was showing signs of unrest, Whakaari remained open to tourism. Forty-seven people were reported to have been on Whakaari, or White Island, when the eruption happened. Twenty-one people have died.

    A month later, Taal volcano in the Philippines erupted and spewed a 15-kilometer tall ash plume into the sky. Lava fountains, sulfuric gas, volcanic earthquakes, and more ash plumes followed. Nearly half a million people lived within the 14-kilometer radius danger zone, but only about 70,000 of those people are estimated to have sheltered in evacuation centers. The price of certified breathing masks inflated tenfold after the eruption. The Philippine Department of Agriculture estimated that ash has destroyed roughly US$60 million in crops. Some residents of Taal have lost everything.

    “We live on a very, very active planet volcanically speaking,” said Janine Krippner, a volcanologist at the Smithsonian Global Volcanism Program in Washington, D.C. “Those types of volcanoes and the eruption styles that we’ve seen now could absolutely happen in the United States in a wide range of sizes—from White Island being very small [to] Taal being a moderate eruption which has the potential to be bigger,” she said.

    It has been 40 years since Mount St. Helens in Washington state erupted. On 18 May 1980, the event killed 57 people, including a volcanologist monitoring the ongoing activity. Since then the volcano experienced some sustained eruptive activity between 2004–2008, largely creating a lava dome beneath the surface, but occasionally sending up some ash. That means it’s been 40 years since U.S. agencies have had to coordinate to keep a major eruption on the mainland from becoming a public health crisis—and experts have found that it’s long past time for a more modern game plan.

    It’s About Who You Know…

    A lot of recent interagency work has focused on bringing volcano response plans in line with the newest science, response structures, and communication platforms.

    Regional and state emergency divisions have kept an ongoing dialogue with the Cascades Volcano Observatory (CVO) on the hazards specific to their areas. The National Science Foundation, NASA, the U.S. Geological Survey (USGS), and the National Academies of Sciences, Engineering, and Medicine conducted a 2-year investigation about how to improve eruption forecasting. Volcanologists, too, have been developing a research coordination network to organize scientific investigations of an eruption, which will inform future response plans.

    In 2018, the eruption of Kīlauea in Hawaii became a proving ground for some of these new response networks.

    Lava bursts from a fissure on the flanks of Kīlauea volcano. As new lava flows and as Kilauea evolves, new landscapes in southeastern areas of the island of Hawai‘i are beginning to take shape. Credit: Mario Tama/Staff/Getty Images News/Getty Images

    Local response teams, USGS, the Federal Emergency Management Agency, and scientists worked together to gather and disseminate information to affected populations. Many of those involved consider the overall response a great success.

    Volcano experts meet regularly to discuss eruption forecasting and hazard modeling. But there’s still more work to be done in understanding the health risks form volcanoes and coming up with action plans to mitigate those risks.

    In the current framework, response would start at the city level, the Centers for Disease Control and Prevention’s Agency for Toxic Substances and Disease Registry (CDC ATSDR) told Eos in a statement. “Local authorities could declare an emergency or disaster and likely would request state assistance. The governor of the state would request federal help if needed. The state request could prompt a presidential declaration and the National Response Framework would activate under the Federal Emergency Management Agency (FEMA).” The National Response Framework, a federal guide to disaster and emergency response, was not in place when Mount St. Helens erupted but has since been used to guide the response to eruptions in Alaska, Hawaii, and the Philippines, ATSDR said.

    “At the eruption of Mount St. Helens in 1980…there were many agencies and thousands of individuals involved in all aspects of the disaster,” explained Peter Baxter, a volcano health expert at the University of Cambridge in the United Kingdom. Baxter, who was part of the response team in 1980, said that the eruption was an “unknown entity” in terms of the human health impacts and the practical challenges of ash deposits in community.

    “People had to learn from scratch,” he said. “Although some of the lessons have been relearned at other volcanoes around the world since, a lot of valuable practical experience is being lost as people retire.”

    “When you do disaster response work, you want to have relationships in place,” said David Damby, who researches the health impacts of eruptions at the USGS California Volcano Observatory in Menlo Park. “During a crisis it’s really hard to meet people and spin up a working relationship on the spot.” If an emergency manager needs a particular piece of information about an ongoing disaster, he said, the key to responding quickly is knowing ahead of time who holds that information.

    …And Also What You Know

    Before the Mount St. Helens event, the last time a major volcano had erupted in the conterminous United States was the 1914 Lassen Peak eruption in California. Unlike the very active volcanoes in Hawaii and Alaska, active volcanoes in the rest of the country erupt twice a century on average. That makes it difficult to predict the potential health hazards that stem from any one specific volcano.

    Mount St. Helens spawned a new field of science concerned with the health impacts of volcanoes in the short and long term. As far as case studies go, that eruption is still one of the most extensively studied to date, but it’s still just one example of the type of eruption that might take place. Volcanologists, out of necessity, study examples from around the world to learn more about what the next Cascades eruption might look like.

    “There was an eruption of El Chichón in 1982 in southern Mexico, and 1,500 people died from pyroclastic flows,” said Carolyn Driedger. “People were not organizing. They had not built trusting relationships with their local communities at risk.” Driedger, a hydrologist and outreach coordinator at CVO in Vancouver, Wash., also witnessed and responded to the Mount St. Helens eruption.

    Then came the eruption of Nevado del Ruiz, Colombia, in 1985 and the Armero tragedy, in which more than 20,000 people in the city of Armero died as a result of mudflows issuing from the eruption.

    “Scientists came into [Armero] and tried to talk to local people, but…they weren’t trusted,” Driedger said. “There were vested business interests that were interfering with the messaging. The lahar came through.”

    A lahar is a volcanic mudflow, Driedger explained. “It’s debris and mud and boulders and anything the flow can pick up and carry.”

    “It was just your worst nightmare,” she said. “It was a dark and stormy night, 11:30 at night, when the lahar came through; 25,000 people died. That showed us lahars are huge hazards and getting information about these hazards to people is so important.”

    From the 1991 eruption of Pinatubo, Philippines, “we learned a lot about eruption prediction and how lahars can affect areas for generations after the initial occurrence,” Driedger said. “Now we know it’s not over when it’s over.”

    Other scientific disciplines aid volcanic research, too. “There’s been a lot done on anthropogenic pollution, for example,” Damby said. “Understanding the impact of particulate matter on people’s health is something that we’re really tuned into because volcanic ash, at the end of the day, is particulate matter.”

    Volcanologists have spent decades building a body of knowledge about how a volcanic eruption might make people sick. That knowledge can be of critical use to agencies and health professionals who don’t exclusively deal with volcanoes.

    “If you’re a health professional who’s never dealt with a volcanic eruption before—which anyone in the U.S. who didn’t respond to 1980 Mount St. Helens is in that same boat—then it’s nice to be able to have the USGS say, ‘Here’s what we know. Here’s what problems might be. Here’s what we need to test for,’” Damby said.

    Evolving Eruptions

    However, predicting an eruption’s hazards is not as easy as saying “Volcano X will produce Hazard X” and “Volcano Y will produce Hazard Y.”

    “Volcanic eruptions can evolve,” Krippner said. “They can get bigger or smaller, or they can pause and then continue. The different hazards can change through that time as well and the extent of those hazards.”

    Disaster mitigation plans work best when the people at risk understand those risks. “There are areas which are excelling at this, but generally speaking, every single aspect of volcanism seems to be misunderstood,” she said.

    For example, simply using the word “smoke” instead of “ash” implies a different set of health hazards and protection measures. “I’d say everything—the terminology, what the hazards are, what they mean for people, what the impacts to people actually are, and how people can stay safe—every single aspect of volcanology has to be better understood by the community,” said Krippner. She noted that official communications about the 2018 Kīlauea eruption were superb.

    “What we focus on the most, because it puts the most people in immediate harm’s way, is lahars,” said Brian Terbush, who heads the earthquake and volcano program at the Washington State Emergency Management Division.

    “All of our volcanoes have a lahar potential and especially the larger ones with huge glacier cover that have river drainages that go into populated areas, such as Mount Rainier,” Terbush said. “About 80,000 people could potentially be at risk from the lahars.” That’s just those at risk from the most immediate lahars near Mount Rainier, Terbush said. Downriver lahars, some experts say, could endanger more than 100,000 residents, employees, and tourists.

    “They are highly destructive,” Driedger added, “so it’s maybe less a health hazard and more a matter of life and death as to your getting out of the way.”

    An eruption of Mount Rainier would cause lahars to sweep through the surrounding area and toward the Puget Sound. Many of the cities at risk for lahars plan and practice evacuation routes. Credit: USGS

    And then, of course, there is volcanic ash. “When ash falls, everything that is covered is impacted and that includes the air,” she said. “Most of the time ash is a nuisance to people, but the people who already have compromised breathing are at risk just as they would be in a place with dense pollution or smoke in the air or a dust storm.”

    Volcanologists and emergency responders are using ash dispersion models, like Ash3d, more often. These models use weather data from the National Oceanic and Atmospheric Administration (NOAA) to predict what areas might experience ashfall. Information from NOAA is also needed after an eruption has ended, when ash can be resuspended in the air by wind and continue to endanger people with compromised breathing.

    “When an eruption is developing, it’s a very confusing time,” Krippner said. “There’s a lot of conflicting information. Scientists are figuring out what exactly is happening, how big this eruption might be, and what areas are being impacted. The groundwork needs to be done beforehand.”

    It’s Not Over When It’s Over

    There’s still a lot of work to be done assessing the long-term health impacts of an eruption, including the secondary health impacts that can occur long before or long after an eruption.

    The sometimes-prolonged period of anticipation preceding an eruption can affect the mental health of emergency managers and the at-risk population. “Even before the lahar even happens…there’s the mental stress of knowing what can happen in your beloved community. I don’t discount that as a medical issue,” Driedger said.

    Sometimes eruptions build up slowly over months, Terbush added, but sometimes they can escalate in a matter of hours (as happened with Taal). For emergency managers, “just the unpredictability of what’s actually going to happen in an eruption, unpredictability in the timeline and unpredictability of which hazards are going to be impactful… if people are activated and responding, especially media response for all that time, that is going to wear on everybody involved.”

    And then there are the myriad of ways that ashfall, lahars, and, to a lesser extent, lava flows, damage critical infrastructure that protects public health. “All the health issues related to relocations—not just temporary evacuation but in many cases final relocation—all those health issues, mental and physical, are applicable with lahars,” Driedger said.

    Ashfall and lahars can cause power outages and leave hospitals and at-home medical devices without power. Wet ash slicks roads and reduces visibility, which can lead to car accidents. Ash can damage a plane’s jet engines, which can hinder evacuation and relief efforts, she added. Local transit authorities, the U.S. Department of Transportation, or the National Guard might aid an evacuation.

    Toxic salts, or leachates, can form on ash while its still in the plume and then wash out into groundwater after ashfall. Livestock that eat contaminated grass or soil can get sick or die.

    “It’s easy to just say ash is ash is ash,” Damby said. “But depending on the composition of the volcano that it erupted from, each ash sample will differ from every other ash sample erupted at a different volcano.” Ash particles around 2.5 and 10 micrometers in size are particularly bad for respiratory health.

    Lahars sweep away bridges, buildings, cropland, and forests, and they can also threaten the local water supply for years. “Lahars are the lasting legacy of volcanic eruptions,” Driedger said. Lahar damage to water treatment plants can lead to higher disease rates. Sediment that is resuspended in water and moved down the valley can keep land unsuitable for settling for generations, she said. Agencies like the CDC, National Institutes of Health, U.S. Department of Agriculture, and Environmental Protection Agency might be called upon to assess land and water toxicity and help recovery efforts.

    And although lava generally moves slow enough that people can get out of the way, lava flows “can gobble up plenty of good orchard and agricultural space that can impact people,” Driedger added. “When you impact personal economies or the economy of the community, you are impacting the health of the people within it.”

    Plan, Practice, Educate, Communicate

    In the time between the recent Whakaari and Taal eruptions, there were actually dozens of volcanoes erupting around the world. “So to only have two making the news in a month or so shows you how little people are actually aware of the amount of activity we have on this planet,” Krippner said.

    Moreover, the unpredictability of eruption hazards presents a challenge for putting together an effective response plan, Terbush said. “Overall, there’s been a shift at the county and local levels with the recognition that any volcanic disaster is going to affect every area a little bit differently.” In areas that were affected by Mount St. Helens and those in the possible path of lahars, there is a cultural awareness of the dangers people might face.

    “The city of Puyallup has been excellent [in volcano readiness],” Terbush said. “This is one of the [municipalities] immediately in Mount Rainier’s lahar zone. This past year they evacuated 9,000 students, did a full school drill of 20 schools.” The drill, which took place on 17 May 2019, was the largest volcano evacuation drill in U.S. history.

    Volcano hazard work groups throughout the Cascade region bring emergency managers from local, regional, state, and tribal areas together with volcano experts to develop coordinated action plans. More cities every year practice lahar evacuation plans like Puyallup’s. Regional volcano observatories work with policy makers to make land use decisions that consider volcano hazards.

    But Driedger argues that volcano awareness and preparedness cannot end at the borders of Washington and Oregon. “Volcanic eruptions are pretty much out of the modern-day person’s personal experience,” she said. “Earthquakes you can feel—you know what a rumble is. You understand the concept of flooding or of a wind storm or a snow storm. But with volcanoes, they’re so multifaceted. It takes an extra amount of effort for us to talk about it with people and get them to understand. They fail to recognize that an eruption in Alaska can affect them in Wisconsin.”

    “We live in such a global society now, too,” she added. “People come to volcanic areas, and they don’t understand what the threats are….It’s the residents and it’s people who visit there, and it’s the taxpayers who are all funding risk reduction measures in some way or another.”

    Raising the base-level understanding of volcano hazards, Krippner said, will also go a long way toward combating the deluge of misinformation that spreads around the globe at lightning speed. In a crisis, finding good information fast saves lives.

    “If we have more sources of information that are consistent, easy to find, and [distributed] in more ways,” Krippner said, “and if we have people with larger followings out there that can point to these things rapidly, I think that would begin to solve the problem.”

    See the full article here .


    Please help promote STEM in your local schools.

    Stem Education Coalition

    Eos is the leading source for trustworthy news and perspectives about the Earth and space sciences and their impact. Its namesake is Eos, the Greek goddess of the dawn, who represents the light shed on understanding our planet and its environment in space by the Earth and space sciences.

  • richardmitnick 9:43 am on March 13, 2020 Permalink | Reply
    Tags: "Mapping Lightning Strikes from Space", Eos, Geostationary Lightning Mapper (GLM) instruments attached to the satellites., GOES-R NOAA satellite, If lightning strikes anywhere in the Western Hemisphere odds are it has already been detected and mapped by satellite-bound cameras orbiting some 35000 kilometers above Earth., This capability is important for public safety because “the majority of injuries and fatalities occur just before the rain has started or just after the rain has ended.   

    From Eos: “Mapping Lightning Strikes from Space” 

    From AGU
    Eos news bloc

    From Eos

    Richard J. Sima

    A new technique spatially tracks lightning in real time and has been adapted by the National Weather Service.

    Credit: Unsplash/Josep Castells

    If lightning strikes anywhere in the Western Hemisphere, odds are it has already been detected and mapped by satellite-bound cameras orbiting some 35,000 kilometers above Earth.

    Lightning flashes are more typically mapped from ground-based networks using radio frequencies to generate precise data on the order of meters. However, ground-based systems have a limited line of sight. The view from a satellite does not, for example, need to “account for things like tree lines or city skylines or even just general dissipation over distance,” said Michael Peterson, an atmospheric scientist at Los Alamos National Laboratory in New Mexico.

    The idea of using a satellite to detect lightning has been around since at least the 1980s, but with the launch of the National Oceanic and Atmospheric Administration’s (NOAA) Geostationary Operational Environmental Satellite–R Series (GOES-R) weather satellites starting in 2016, researchers and forecasters have attained unprecedented levels of lightning data from the Geostationary Lightning Mapper (GLM) instruments attached to the satellites.


    An interdisciplinary team of researchers now has developed a technique that can map out the lightning flashes GLM detects across the entire Western Hemisphere in real time.

    “It’s not only a matter of being able to see more, but being able to see things completely,” said Peterson, who was not involved in the study.

    The new technique was reported in the Journal of Geophysical Research: Atmospheres in December 2019 and has been adapted for use by the U.S. National Weather Service (NWS).

    Seeing Lightning More Completely

    The GLM is essentially a video camera in space that captures lightning flashes across the Western Hemisphere at 500 frames per second. “There’s very little dead time. No matter how rare the lightning flash is, you’re probably going to see it,” Peterson said.

    Five minutes of lightning from the Geostationary Lightning Mapper show small areas of high lightning flash rates (maximum of about 100 per minute) and a few very large flashes with areas of thousands of square kilometers. Credit: NOAA/NESDIS/Scott Rudlosky.

    But that deluge of data comes with a downside. “You can’t send all that video data down to the ground,” said Eric Bruning, an atmospheric scientist at Texas Tech University in Lubbock and lead author on the study. Instead, the data are sent as pixels attached to geolocation information that clustered into lightning flashes. “For a lot of users, it’s just really challenging to even know what to do with those data,” he said.

    The new technique reconstructs and spatially maps the lightning flashes while retaining the quantitative physical measurements made by the GLM.

    “In a way, it’s just restoring the video nature of the camera,” Bruning said.

    The researchers demonstrated that this space-based lightning mapping technique can distinguish the many tiny flashes of lightning within thunderstorm cores and the large lightning flashes that are part of mesoscale storm systems.

    Myriad Applications

    The technique’s application for weather forecasters was readily apparent and rapidly developed over the course of a year to be used by NWS. The process required getting the product to work with NWS operational display systems, matching data formats, making it timely, and not allowing it to fail, Bruning said. In adapting the tool for practical applications, he said, “you find all the bugs that you just ignore as a researcher in your code.”

    Using this technique, it would be possible to track the origin of so-called bolts from the blue that occur without rain, said Christopher Schultz, a research meteorologist at NASA’s Short-term Prediction Research and Transition Center in Huntsville, Ala., and coauthor on the study. Seeing the origin of the flash is important to anticipate future lightning and is not possible with traditional ground-based lightning data. This capability is important for public safety because “the majority of injuries and fatalities occur just before the rain has started or just after the rain has ended,” Schultz said.

    “Right now the main users are [at] the National Weather Service, and that’s mainly because the instrument is brand-new to the public,” said Schultz. He expects that as the technology evolves and it gets into the public’s hands, it will become more widely used, like radar is now.

    “It is certainly useful to be used in real time, but it’s not as useful as it could be,” Peterson said. One major caveat with the technique is that it relies on the data provided by NOAA and assumes their veracity. “Unfortunately, the algorithm is not perfect.”

    Because of the complexity of the data, large flashes of lightning are automatically split into multiple flashes, explained Peterson. He recently published a new processing system [JGR Atmospheres] to stitch these smaller flashes back together. “Now, this isn’t a huge deal in terms of overall statistics. We’re talking 4% to 8% of all lightning depending on what storm you’re looking at.”

    Still, the latest study adds a powerful new tool for scientists and forecasters studying lightning. The technique, which is available as open-source software, also grants “the ability to use lightning to monitor the climate and also to even study storm processes in places where we don’t have the rich radar network that we have in the U.S.,” Bruning said.

    “I think it’s important to keep that global perspective in mind,” he added.

    See the full article here .


    Please help promote STEM in your local schools.

    Stem Education Coalition

    Eos is the leading source for trustworthy news and perspectives about the Earth and space sciences and their impact. Its namesake is Eos, the Greek goddess of the dawn, who represents the light shed on understanding our planet and its environment in space by the Earth and space sciences.

  • richardmitnick 3:41 pm on February 21, 2020 Permalink | Reply
    Tags: "Deciphering Electron Signatures in Earth’s Magnetic Tail", , , , , Eos   

    From Eos: “Deciphering Electron Signatures in Earth’s Magnetic Tail” 

    From AGU
    Eos news bloc

    From Eos

    Mark Zastrow

    The four spacecraft of NASA’s Magnetospheric Multiscale mission travel through Earth’s magnetic field in this illustration. Researchers recently used data from the mission to study electron signatures during a magnetic reconnection event in Earth’s magnetic tail. Credit: NASA

    Space envelops our planet entirely, but when it comes to space weather, a few regions are particularly important.

    One of these regions is in Earth’s magnetotail roughly 160,000 kilometers above the planet’s nightside, where the planetary magnetic field is blown back by the solar wind and its field lines are stretched until they cross each other again. During geomagnetic storms, these field lines break and reconnect, releasing energy stored in the magnetic field like a rubber band snapping. These magnetic explosions blast the nightside of the Earth with radiation and charged particles, which can threaten infrastructure like satellites and power grids.

    Now Li et al. [Geophysical Research Letters] have analyzed unique spacecraft measurements taken right at the tip of Earth’s magnetotail during a reconnection event. The data were collected in August 2017 by the Magnetospheric Multiscale (MMS) mission, a quartet of NASA spacecraft orbiting Earth.

    During this event, MMS flew through the reconnection region traveling northward, a trajectory that gave the craft a prime view of a phenomenon known as electron meandering. In an unruffled, purely uniform magnetic field, the motion of electrons should be simple and symmetric: spiraling along magnetic field lines like beads spinning on a string.

    But according to MMS data returned since its launch in 2015, electrons near reconnection sites often drift to one side of the magnetic field lines, leading to crescent-shaped electron distributions. Scientists have sought to understand the cause of this crescent signature—whether it’s related to magnetic fields or possibly a combination of magnetic and electric fields.

    In the new study, the researchers found electron crescents just above and below the reconnection site, which they say are partly explained by the twisting of the magnetic field during reconnection. However, this asymmetric electron motion was found farther from the midplane of this region of the magnetotail than expected for high-energy electrons, suggesting that another mechanism is at play.

    The authors single out a likely culprit: Electric fields that are induced by flowing electrons in the presence of a magnetic field. This effect—known as the Hall effect—is thought to enhance magnetic reconnection. Indeed, the stronger the electric field readings collected by MMS were, the more pronounced the crescent signature became. This finding suggests that electron crescents observed in the magnetotail are caused by a combination of magnetic and electric fields.

    See the full article here .


    Please help promote STEM in your local schools.

    Stem Education Coalition

    Eos is the leading source for trustworthy news and perspectives about the Earth and space sciences and their impact. Its namesake is Eos, the Greek goddess of the dawn, who represents the light shed on understanding our planet and its environment in space by the Earth and space sciences.

  • richardmitnick 10:08 am on February 21, 2020 Permalink | Reply
    Tags: "'Glacial Earthquakes' Spotted for the First Time on Thwaites", , , Eos, , That’s bad news scientists agree because Thwaites helps hold back the West Antarctic Ice Sheet from flowing into the sea., Thwaites is responsible for about 4% of global sea level rise., Thwaites’s floating ice shelf is degrading.   

    From Eos: “‘Glacial Earthquakes’ Spotted for the First Time on Thwaites” 

    From AGU
    Eos news bloc

    From Eos

    17 February 2020
    Katherine Kornei

    These seismic events, triggered by icebergs capsizing and ramming into Thwaites, reveal that the glacier has lost some of its floating ice shelf.

    Icebergs calving off Thwaites Glacier occasionally capsize and launch seismic waves that travel hundreds of kilometers. Credit: David Vaughan, British Antarctic Survey.

    Icebergs calve off glaciers all the time. But most don’t pitch backward, capsize, and send seismic waves radiating out for thousands of kilometers.

    New research reports that such “glacial earthquakes” have now been detected for the first time on Antarctica’s Thwaites Glacier. These observations confirm that Thwaites’s floating ice shelf is degrading. That’s bad news, scientists agree, because the glacier helps hold back the West Antarctic Ice Sheet from flowing into the sea.

    Flipping Icebergs

    Scenarios for iceberg calving at fast tidewater glaciers. Buoyancy-driven calving is likely to produce icebergs with small width-to-height ratios that will capsize against the terminus front. The generated iceberg-to-terminus contact force is responsible for the production of glacial earthquakes. Credit: Sergeant et al., 2019, Annals of Geology

    Thwaites Glacier, roughly the size of the state of Florida, is one of the largest sources of ice loss in Antarctica and is responsible for about 4% of global sea level rise.

    It regularly sheds icebergs hundreds of meters on a side into the Amundsen Sea, but some of these chunks of ice aren’t just drifting away, said J. Paul Winberry, a geophysicist at Central Washington University in Ellensburg who led the new study. Thanks to their shape, they’re capsizing. “They’re taller than they are wide. They’re top-heavy, and they want to flip over,” said Winberry.

    Over several tens of seconds, these icebergs roll backward and collide with the new edge of Thwaites. “They bang the front of the glacier,” said Winberry.

    Those collisions launch seismic waves that can be picked up by detectors hundreds and even thousands of kilometers away. Last year, Winberry was combing through seismic data and serendipitously discovered two of these collisions. “We got really lucky,” said Winberry.

    By triangulating the signals recorded by seven seismic stations spread across West Antarctica, he and his colleagues determined that the events had occurred on the front of Thwaites.

    Using optical and radar satellite imagery acquired within minutes of the seismic events, both of which took place 8 November 2018, the team confirmed that calving had indeed occurred. The researchers counted five capsized icebergs, their icy undersides now exposed. (In radar imagery, such icebergs appear dark—ice reflects radio waves more poorly than snow.)

    Seismology complements satellite imagery when it comes to studying glaciers, said Lucas Zoet, a glaciologist at the University of Wisconsin–Madison not involved in the research. Satellites can obtain high-resolution imagery but typically pass over the same spot on Earth only every few days or, at best, every few hours, Zoet said. Seismological instruments, on the other hand, are always listening. That’s important, he said, because “the real interesting part might happen in just a couple minutes.”

    All About Ice Shelves

    These glacial earthquakes shed light on Thwaites’s geometry and therefore its future stability.

    For icebergs to capsize, they must be taller than they are wide. That’s common in Greenland [Annals of Geology above] because most glaciers there don’t contain floating ice shelves, said Winberry. “The edge of a glacier is grounded or close to touching the bedrock.” That ice thickness translates into icebergs being taller than they are wide, which renders them unstable in the water.

    But Antarctic glaciers tend to have floating ice shelves, so their iceberg progeny are typically wider than they are tall and, accordingly, don’t produce glacial earthquakes. Thwaites appears to be an anomaly.

    “This portion of Thwaites Glacier is distinct from the rest of Antarctica in that it’s lost most of its floating ice shelf,” said Winberry. “We think that’s what’s going to happen to the rest of Thwaites going forward.” Ice shelves, by literally getting hung up on islands and underwater ridges, help stabilize glaciers by acting like buttresses.

    Tiny Temblors, Too

    The seismological data that Winberry and his colleagues analyzed revealed more than just two glacial earthquakes—there were also over 600 tiny temblors in the 6 days leading up to the calving.

    “We think we’re hearing the accelerating failure of the ice before it calves off,” said Winberry.

    That’s an important window into how Thwaites is changing, he said. These observations can be used to inform models of calving, Winberry and his colleagues suggest.

    These results were published last month in Geophysical Research Letters.

    In the future, Winberry and his team plan to do a more systematic search for glacial earthquakes on Thwaites. They’re interested in determining possible triggering events that might drive calving, like big storms or moving sea ice.

    See the full article here .


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  • richardmitnick 4:08 pm on February 18, 2020 Permalink | Reply
    Tags: "Fluid Pressure Changes Grease Cascadia’s Slow Aseismic Earthquakes", , , , , Eos,   

    From Eos: “Fluid Pressure Changes Grease Cascadia’s Slow Aseismic Earthquakes” 

    From AGU
    Eos news bloc

    From Eos

    Mary Caperton Morton

    Twenty-five years’ worth of data allows scientists to suss out subtle signals deep in subduction zones.

    Cascadia subduction zone

    Cascadia plate zones

    The study region followed the coast of Vancouver Island in British Columbia, one of the source regions for slow earthquakes along the Cascadia Subduction Zone. Credit: NASA

    Not all earthquakes make waves. During slow “aseismic” earthquakes, tectonic plates deep in subduction zones can slide past one another for days or even months without producing seismic waves. Why some subduction zones produce devastating earthquakes and tsunamis while others move benignly remains a mystery. Now a new study is shedding light on the behavior of fluids in faults before and after slow-slip events in the Cascadia Subduction Zone.

    Aseismic earthquakes, also known as episodic tremor and slip, were discovered about 20 years ago in the Cascadia Subduction Zone, where oceanic plates are descending beneath the North American plate at a rate of about 40 millimeters per year.


    Vancouver profile

    Oregon profile

    This 1,000-kilometer-long fault has a dangerous reputation but has not produced a major earthquake since the magnitude 9.0 megathrust earthquake and tsunami that struck on 26 January 1700. Scientists think that some of Cascadia’s energy may be dissipated by regular aseismic events that take place deep in the fault zone roughly every 14 months.

    Episodic tremor and slip occur deep in subduction zones, and previous studies have suggested that these slow-slip events may be lubricated by highly pressurized fluids. “There are many sources of fluids in subduction zones. They can be brought down by the descending plate, or they can be generated as the downgoing plate undergoes metamorphic reactions,” said Pascal Audet, a geophysicist at the University of Ottawa in Ontario and an author on the new study, published in Science Advances.

    “At depths of 40 kilometers, the pressure exerted on the rocks is very high, which normally tends to drive fluids out, like squeezing a sponge,” Audet said. “However, these fluids are trapped within the rocks and are virtually incompressible. This means that fluid pressures increase dramatically, weakening the rocks and generating slow earthquakes.”

    This 1,000-kilometer-long fault has a dangerous reputation but has not produced a major earthquake since the magnitude 9.0 megathrust earthquake and tsunami that struck on 26 January 1700. Scientists think that some of Cascadia’s energy may be dissipated by regular aseismic events that take place deep in the fault zone roughly every 14 months.

    Eavesdropping on Slow Quakes

    To study how fluid pressures change during slow earthquakes, lead author Jeremy Gosselin, also at Ottawa, and Audet and colleagues drew upon 25 years of seismic data, spanning 21 slow-earthquake events along the Cascadia Subduction Zone. “By stacking 25 years of data, we were able to detect slight changes in the seismic velocities of the waves as they travel through the layers of oceanic crust associated with slow earthquakes,” Audet said. “We interpret these changes as direct evidence that pore fluid pressures fluctuate during slow earthquakes.”

    Audet and colleagues are still working to identify the cause and effect of the pore fluid pressure changes. “Is the change in fluid pressure a consequence of the slow earthquake? Or is it the opposite: Does an increase in pore fluid pressure somehow trigger the slow earthquake? That’s the next big question we’d like to tackle.”

    “I’m surprised and impressed they were able to isolate these signals,” said Michael Bostock, a geophysicist at the University of British Columbia in Vancouver who was not involved in the new study. “They’re very subtle, but they’re all pointing in the same direction.”

    Theoretical models, as well as other seismic studies on subduction zones in Japan and New Zealand, have offered supporting lines of evidence that pore fluids are redistributed at the boundaries of tectonic plates during slow-slip events, Audet said. “Other studies have offered somewhat indirect evidence for this idea, but our study offers the first direct evidence that fluid pressures do in fact fluctuate during slow earthquakes.”

    The next steps will be to conduct similar seismic studies on other subduction zones, Bostock said. It’s too soon to say whether this fluid behavior is universal to all slow-earthquake zones, but “there may be other factors at play as well, such as temperature and pressure, that create a sweet spot where slow earthquakes are more likely to occur,” he said. The right combination of overlapping factors may help explain why some fault zones record more aseismic events than others.

    Whether these changes in fluid pressures could be used to predict where and when a slow-slip event might occur is unknown, Bostock said, although “slow earthquakes are already more predictable than regular earthquakes.” In Cascadia, for example, they’re known to occur about every 14 months, give or take, for reasons that remain unclear. “Prediction is the holy grail of earthquake science, but it’s fraught with difficulties. Tectonic faults, despite their grand scale, are very sensitive to perturbations in ways we don’t clearly understand yet.”

    See the full article here .


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  • richardmitnick 4:36 pm on February 4, 2020 Permalink | Reply
    Tags: "China Challenges U.S. Science Dominance", Eos   

    From Eos: “China Challenges U.S. Science Dominance” 

    From AGU
    Eos news bloc

    From Eos

    A recent Congressional hearing and National Science Board report show that U.S. leadership faces growing global competition.


    Randy Showstack

    “The best way to lead the future is to invent it,” Diane Souvaine, chair of the National Science Board (NSB), testified at a 29 January congressional hearing about the state of U.S. competitiveness with China and other countries on science and technology.

    However, Souvaine and other witnesses, as well as members of Congress from both sides of the aisle, said that the United States needs to do more to maintain its leadership in these areas in the face of surging expenditures by China.

    The hearing of the House Committee on Science, Space, and Technology followed up on NSB’s release of its “State of U.S. Science and Engineering 2020” report. That report, which is part of congressionally mandated Science and Engineering Indicators, shows that the United States in 2017 still maintained its lead over China regarding total research and development (R&D) expenditures.

    Souvaine noted in her written testimony, though, that trend lines in a figure in the report “suggest that in 2019 China may have surpassed the U.S. in total R&D expenditures.” In her oral testimony, Souvaine said that the NSB “believes that China has already surpassed the United States in R&D investments.” The NSB, which governs the National Science Foundation, serves as an independent adviser to the president and Congress.

    In 2017, U.S. gross domestic expenditures on R&D totaled $548 billion in purchasing power parity (PPP) exchange rates and accounted for 25% of global R&D, down from 37% in 2000. In 2017, China’s PPP expenditures on R&D equaled about $500 billion and made up 23% of global R&D. In addition, China accounted for 32% of worldwide R&D growth between 2000 and 2017, whereas the United States accounted for 20% of growth. The European Union was third, accounting for 17% of growth.

    “S&E [science and engineering] is now truly a worldwide enterprise—connected, complex, and interdependent, with more players and opportunities and humanity’s collective knowledge growing exponentially. While science is the endless frontier, we’re not the only explorer,” Souvaine said, referencing the landmark 1945 report Science: The Endless Frontier by Vannevar Bush.

    “Staying at the forefront of S&E is essential for our economy and our security,” she added. “As other countries have invested in their own research enterprises, our share of global discovery and innovation has declined and will likely continue to decline. We are no longer the uncontested leader in S&E and we must adapt to changes in the world and in our country.”

    Shared Priorities

    Committee chair Rep. Eddie Bernice Johnson (D-Texas) said that U.S. leadership in science and technology has given U.S. companies a competitive advantage. However, she warned that the country “has already begun to face the consequences of our inability to make strategic and sustained long-term investments in our science and technology enterprise.”

    Although the federal government occasionally has “risen to the challenge” of providing more generously funded science and technology, “in the last 15 years, the nondefense research and development budget has stagnated,” Johnson said. “We have what it takes to lead. The question is, will we do what it takes?”

    At the hearing, the committee’s ranking Republican, Rep. Frank Lucas (R-Okla.), said he is “a supporter of doubling the money that we spend on federally funded basic research in the next decade.”

    Legislation that Lucas introduced on 28 January, the Securing American Leadership in Science and Technology Act, would authorize a doubling of basic research funding over the next decade at the Department of Energy, National Science Foundation, National Institute of Standards and Technology, and National Oceanic and Atmospheric Administration.

    “I recognize that we are the minority party and that we do not get to set the agenda,” Lucas said. “But I believe we have many shared priorities and I hope this legislative package will start a bipartisan conversation about what we need to do to ensure America leads the technological revolution of the 21st century.”

    Committee member Rep. Jerry McNerney (D-Calif.) commented that hearing Lucas say he strongly favors doubling the federal R&D budget “has got to be the most exciting thing that we’ve seen here” at the hearing.

    Maintaining U.S. Leadership

    Souvaine noted that the United States continues to lead in some key areas and that the U.S. “can-do attitude” can help maintain the country’s leadership. “Amid this dramatic growth in China’s R&D investment, it is crucial to note that the U.S. maintains a significant advantage in basic research—the seed corn for our entire S&E enterprise. In 2017, the U.S. invested $92 billion in basic research; China came in a distant second, investing $27 billion,” she said.

    In addition to highlighting the need for increased U.S. investments in R&D, Souvaine said the country “must move aggressively to grow and diversify our domestic STEM [science, technology, engineering, and mathematics] workforce” and acknowledge the near-term reliance on foreign-born talent. She also called for recommitting to partnerships among government, universities, and the private sector, among other measures.

    “This is our ask. Let’s not merely react to anxieties from global competitions, concern about security threats, or angst about constrained budgets. Instead, let’s act now before lagging indicators show that it’s too late,” Souvaine said.

    See the full article here .


    Please help promote STEM in your local schools.

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  • richardmitnick 8:31 am on January 10, 2020 Permalink | Reply
    Tags: "Pinpointing Emission Sources from Space", , , Eos, , ESA Copernicus Sentinel-5P with Tropospheric Monitoring Instrument (TROPOMI), New research combines satellite images with wind models to locate sources of air pollution.   

    From ESA via Eos: “Pinpointing Emission Sources from Space” 

    ESA Space For Europe Banner

    From European Space Agency – United space in Europe


    From AGU
    Eos news bloc

    From Eos

    2 January 2020
    Mary Caperton Morton

    Satellite data combined with wind models bring scientists one step closer to being able to monitor air pollution from space.

    New research combines satellite images with wind models to locate sources of air pollution. This map shows emissions of nitrogen oxides in western Germany, dominated by lignite power plants. Credit: Data from TROPOMI/ESA; created by Steffen Beirle.

    Nitrogen oxides are some of the main ingredients in air pollution, smog, acid rain, and greenhouse gas–driven warming. Quantifying large-scale sources of nitrogen oxide pollution has long proved challenging, making regulation difficult, but now a new high-resolution satellite monitoring system, combined with wind modeling, is providing the tools needed to remotely monitor nitrogen oxide emissions anywhere in the world from space.

    The Tropospheric Monitoring Instrument (TROPOMI) on board the European Space Agency’s Copernicus Sentinel-5 Precursor satellite, launched in October 2017, offers “unparalleled spatial resolution” of greenhouse gases and pollutants, including nitrogen oxides, carbon monoxide, and methane, over industrial complexes and major cities, said Steffen Beirle, a geochemist at the Max Planck Institute for Chemistry in Germany and lead author of the new study published in Science Advances.

    ESA Copernicus Sentinel-5P with Tropospheric Monitoring Instrument (TROPOMI)

    But it’s not enough to simply image the gas plumes, as they tend to be smeared horizontally by wind currents. To quantify the amount of gas being emitted, the satellite data must be processed to take wind patterns into account, Beirle said. “If you just look at the map of the satellite measurements, you see polluted spots over the east coast of the U.S. and China, for example. The difficulty comes when you try to quantify the emissions coming from those hot spots.”

    The majority of stationary emissions (as opposed to mobile emissions from vehicles) of nitrogen oxides (NO and NO2, commonly combined as NOx) come from power plants. To quantify emissions from individual power plants, Beirle and colleagues combined TROPOMI data with three-dimensional models of wind spatial patterns. “Previous approaches have taken wind data into account, but not in this kind of systematic way,” he said.

    The team first focused their efforts on Riyadh, the capital of Saudi Arabia. Riyadh is fairly remote from other cities, industrial areas, and other sources that could complicate the emission signal. Initially, the satellite data showed a strong NOx signal centered over Riyadh, smeared to the south and east by prevailing winds. Further analysis using the wind models revealed five localized point sources within the smear that corresponded to four power plants and a cement plant.

    In total they found that the city produces 6.6 kilograms of NOx per second, with the four power plants accounting for about half of those emissions. Individually, emissions from Riyadh’s crude oil– and natural gas–powered plants were comparable to emissions from coal-fired power plants in the United States.

    The team also tested their techniques in South Africa and Germany, where cloud cover can make collecting satellite data difficult. They found the method worked well in both places, but with higher uncertainties in quantifying emissions.

    The study represents an important step in being able to monitor greenhouse gas emissions from space, said Andreas Richter, an atmospheric chemist at the University of Bremen in Germany who was not involved in the new study.

    “In Germany, industrial facilities are required to track and report their emissions. Where it’s not required, being able to monitor emissions remotely using satellites will be very valuable,” Richter said. The method also has the “potential to validate or check emission inventories that are reported by different countries using different methods, using a consistent methodology globally,” Beirle says. In Germany, the emissions calculated using the new satellite and wind model method “matched up well to the inventory provided by the facilities,” he said.

    Power plants are the primary concern for point source emissions, with large industrial facilities like steel factories and cement plants also contributing significant amounts of nitrogen oxides. Diffused emissions from moving sources such as vehicles are harder to pin down. “The total emission from cities may be as large as from a big power plant, but because it’s not as localized, this particular method doesn’t work as well,” Richter said.

    Beirle and colleagues also hope to apply their methods to other pollutants, such as sulfur dioxide. “We hope to do something similar for sulfur dioxide, but the background noise levels are higher,” he said. “This satellite is opening up a whole new line of inquiry: What other emissions can we track from space? It will be exciting to see what happens in the next few years.”

    See the full article here .


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    The European Space Agency (ESA), established in 1975, is an intergovernmental organization dedicated to the exploration of space, currently with 19 member states. Headquartered in Paris, ESA has a staff of more than 2,000. ESA’s space flight program includes human spaceflight, mainly through the participation in the International Space Station program, the launch and operations of unmanned exploration missions to other planets and the Moon, Earth observation, science, telecommunication as well as maintaining a major spaceport, the Guiana Space Centre at Kourou, French Guiana, and designing launch vehicles. ESA science missions are based at ESTEC in Noordwijk, Netherlands, Earth Observation missions at ESRIN in Frascati, Italy, ESA Mission Control (ESOC) is in Darmstadt, Germany, the European Astronaut Centre (EAC) that trains astronauts for future missions is situated in Cologne, Germany, and the European Space Astronomy Centre is located in Villanueva de la Cañada, Spain.

  • richardmitnick 7:48 am on January 10, 2020 Permalink | Reply
    Tags: "The Ice Giant Spacecraft of Our Dreams", , , , , Eos,   

    From NASA JPL-Caltech via Eos: “The Ice Giant Spacecraft of Our Dreams” 

    NASA JPL Banner

    From NASA JPL-Caltech


    From AGU
    Eos news bloc


    7 January 2020
    Kimberly M. S. Cartier

    The hypothetical dream spacecraft flies over Uranus and past its rings and moons, too. Credit: JoAnna Wendel

    If you could design your dream mission to Uranus or Neptune, what would it look like?

    Would you explore the funky terrain on Uranus’s moon Miranda? Or Neptune’s oddly clumpy rings? What about each planet’s strange interactions with the solar wind?

    The dream spacecraft’s innovative technologies would enable a comprehensive exploration of an entire ice giant system. Credit: JoAnna Wendel.

    Why pick just one, when you could do it all?

    Planetary scientists recently designed a hypothetical mission to one of the ice giant planets in our solar system. They explored what that dream spacecraft to Uranus could look like if it incorporated the newest innovations and cutting-edge technologies.

    “We wanted to think of technologies that we really thought, ‘Well, they’re pushing the envelope,’” said Mark Hofstadter, a senior scientist at the Jet Propulsion Laboratory (JPL) and California Institute of Technology in Pasadena. “It’s not crazy to think they’d be available to fly 10 years from now.” Hofstadter is an author of the internal JPL study, which he discussed at AGU’s Fall Meeting 2019 on 11 December.

    Some of the innovations are natural iterations of existing technology, Hofstadter said, like using smaller and lighter hardware and computer chips. Using the most up-to-date systems can shave off weight and save room on board the spacecraft. “A rocket can launch a certain amount of mass,” he said, “so every kilogram less of spacecraft structure that you need, that’s an extra kilogram you could put to science instruments.”

    Nuclear-Powered Ion Engine

    The dream spacecraft combines two space-proven technologies into one brand-new engine, called radioisotope electric propulsion (REP).

    A spacecraft works much like any other vehicle. A battery provides the energy to run the onboard systems and start the engine. The power moves fuel through the engine, where it undergoes a chemical change and provides thrust to move the vehicle forward.

    Credit: JoAnna Wendel

    In the dream spacecraft, the battery gets its energy from the radioactive decay of plutonium, which is the preferred energy source for traveling the outer solar system where sunlight is scarce. Voyager 1, Voyager 2, Cassini, and New Horizons all used a radioisotope power source but used hydrazine fuel in a chemical engine that quickly flung them to the far reaches of the solar system.

    NASA/Voyager 1

    NASA/Voyager 2

    NASA/ESA/ASI Cassini-Huygens Spacecraft

    NASA/New Horizons spacecraft

    The dream spacecraft’s ion engine uses xenon gas as fuel: The xenon is ionized, a nuclear-powered electric field accelerates the xenon ions, and the xenon exits the craft as exhaust. The Deep Space 1 and Dawn missions used this type of engine but were powered by large solar panels that work best in the inner solar system where those missions operated.

    Xenon gas is very stable. A craft can carry a large amount in a compressed canister, which lengthens the fuel lifetime of the mission. REP “lets us explore all areas of an ice giant system: the rings, the satellites, and even the magnetosphere all around it,” Hofstadter said. “We can go wherever we want. We can spend as much time as we want there….It gives us this beautiful flexibility.”

    A Self-Driving Spacecraft

    With REP, the dream spacecraft could fly past rings, moons, and the planet itself about 10 times slower than a craft with a traditional chemical combustion engine. Moving at a slow speed, the craft could take stable, long-exposure, high-resolution images. But to really make the most of the ion engine, the craft needs onboard automatous navigation.

    “We don’t know precisely where the moon or a satellite of Uranus is, or the spacecraft [relative to the moon],” Hofstadter said. Most of Uranus’s satellites have been seen only from afar, and details about their size and exact orbits remain unclear. “And so because of that uncertainty, you always want to keep a healthy distance between your spacecraft and the thing you’re looking at just so you don’t crash into it.”

    “But if you trust the spacecraft to use its own camera to see where the satellite is and adjust its orbit so that it can get close but still miss the satellite,” he said, “you can get much closer than you can when you’re preparing flybys from Earth” at the mercy of a more than 5-hour communications delay.

    That level of onboard autonomous navigation hasn’t been attempted before on a spacecraft. NASA’s Curiosity rover has some limited ability to plot a path between destinations, and the Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer (OSIRIS-REx) will be able to detect hazards and abort its sample retrieval attempt.

    The dream spacecraft would be more like a self-driving car. It would know that it needs to do a flyby of Ophelia, for example. It would then plot its own low-altitude path over the surface that visits points of interest like chaos terrain. It would also navigate around unexpected hazards like jagged cliffs. If the craft misses something interesting, well, there’s always enough fuel for another pass.

    A Trio of Landers

    With extra room on board from sleeker electronics, plus low-and-slow flybys from the REP and autonomous navigation, the dream spacecraft could carry landers to Uranus’s moons and easily drop them onto the surface.

    Credit: JoAnna Wendel

    “We designed a mission to carry three small landers that we could drop on any of the satellites,” Hofstadter said. The size, shape, and capabilities of the landers could be anything from simple cameras to a full suite of instruments to measure gravity, composition, or even seismicity.

    The dream spacecraft could survey all 27 of Uranus’s satellites, from its largest, Titania, to its smallest, Cupid, only 18 kilometers across. The mission team could then decide the best way to deploy the landers.

    “We don’t have to decide in advance which satellites we put them on,” he said. “We can wait until we get there. We might decide to put all the landers on one satellite to make a little seismic network to look for moonquakes and study the interior. Or maybe when we get there we’ll decide we’d rather put a lander on three different satellites.”

    “Ice”-ing on a Cake

    The scientists who compiled the internal study acknowledged that it’s probably unrealistic to incorporate all of these innovative technologies into one mission. Doing so would involve a lot of risk and a lot of cost, Hofstadter said. Moreover, existing space-tested technology that has flown on Cassini, New Horizons, and Juno can certainly deliver exciting ice giant science, he said. These innovations could augment such a spacecraft.

    At the moment, there is no NASA mission under consideration to explore either Uranus or Neptune. In 2017, Hofstadter and his team spoke with urgency about the need for a mission to one of the ice giant planets and now hope that these technologies of the future might inspire a mission proposal.

    “It’s almost like icing on the cake,” he said. “We were saying, If you adopted new technologies, what new things could you hope to do that would enhance the scientific return of this mission?”

    See the full article here .


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    NASA JPL Campus

    Jet Propulsion Laboratory (JPL)) is a federally funded research and development center and NASA field center located in the San Gabriel Valley area of Los Angeles County, California, United States. Although the facility has a Pasadena postal address, it is actually headquartered in the city of La Cañada Flintridge, on the northwest border of Pasadena. JPL is managed by the nearby California Institute of Technology (Caltech) for the National Aeronautics and Space Administration. The Laboratory’s primary function is the construction and operation of robotic planetary spacecraft, though it also conducts Earth-orbit and astronomy missions. It is also responsible for operating NASA’s Deep Space Network.

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  • richardmitnick 9:20 am on January 8, 2020 Permalink | Reply
    Tags: "Understanding High-Energy Physics in Earth’s Atmosphere", (HEAP)-high-energy atmospheric physics, (TGEs)-thunderstorm ground enhancements, , , Eos, ,   

    From Eos: “Understanding High-Energy Physics in Earth’s Atmosphere” 

    From AGU
    Eos news bloc

    From Eos


    Ashot A. Chilingarian
    Cosmic Ray Division, Yerevan Physics Institute, Yerevan, Armenia

    Thunderstorms present a variety of hazards, including emissions of ionizing radiation. An international group of scientists met at an Armenian observatory to share their findings.

    Armenia’s Lake Kari sits near the top of Mount Aragats. In this summertime view, the south summit is visible in the background. Attendees at a conference in 2019 visited a nearby research station that collects data on atmospheric radiation associated with thunderstorms. Credit: Ashot A. Chilingarian

    All living organisms are continuously exposed to natural radioactivity from Earth’s minerals and atmosphere, as well as from sources beyond the atmosphere. Protecting against the harmful effects of radiation requires us to understand all sources of radiation and the possible ways in which radiation levels are enhanced. Recently, scientists discovered that a given individual’s cumulative radiation exposure can reach significant levels during thunderstorms [Chilingarian et al., 2018 Physical Review D]. Thus, models used for forecasting thunderstorms and other severe atmospheric phenomena need an accurate accounting of radiation in the atmosphere.

    Long-lasting streams of gamma rays, electrons, and neutrons called thunderstorm ground enhancements (TGEs) have been observed in association with thunderstorms. These observations demonstrate that levels of natural gamma radiation in the 10– to 50–megaelectron volt range can jump to 10 times their normal level over the course of several minutes, and levels of gamma rays with energies of hundreds of kiloelectron volts can be doubled for several hours.

    Until recently, the origin of these elevated TGE fluxes was debated. The most popular hypothesis, that the particle bursts were initiated by runaway electrons, had not been confirmed by direct observation. The emerging research field of high-energy atmospheric physics (HEAP) is now shedding light on what causes these particle showers.

    HEAP comprises studies of various physical processes that extend to altitudes of many kilometers in thunderclouds and many hundreds of kilometers in space. Research into TGEs has been active since 2010. Since this time, the Cosmic Ray Division (CRD) of Armenia’s Yerevan Physics Institute has organized international conferences at which HEAP researchers discuss the most intriguing problems of high-energy physics in the atmosphere and explore possible directions for the advancement of collaborative studies. The ninth annual meeting, held in Byurakan, Armenia, in October 2019, provided an environment for discussing important observations of particle fluxes correlated with thunderstorms occurring on Earth’s surface, in the troposphere, and in space.

    Understanding Thunderstorm Phenomena

    The concept of runaway electrons in thunderclouds extends back almost a century. One of the first particle physicists and atmospheric electricity researchers, Nobel laureate Sir C. T. R. Wilson, was the first to recognize that “the occurrence of exceptional electron encounters has no important effect in preventing the acquisition of large kinetic energy by particles in a strong accelerating field” [Wilson, 1925 Mathematical Proceedings of the Cambridge Philosophical Society]. The astronomer Arthur Eddington, referring to this electron acceleration by the strong electric fields in thunderclouds, coined the term “runaway electrons” [Gurevich, 1961 Soviet Physics JETP]. However, until now, this and many other electromagnetic processes in our atmosphere have been only partially understood, and key questions about thundercloud electrification and lightning initiation have remained unanswered.

    HEAP research currently includes three types of measurements. Orbiting gamma ray observatories in space observe terrestrial gamma ray flashes, which are brief bursts of gamma radiation (sometimes with electrons and positrons). Instruments on balloons and aircraft observe gamma ray glows. Detectors on Earth’s surface register TGEs, which consist of prolonged electron and gamma ray fluxes (also neutrons; Figure 1). The durations of these different enhanced particle fluxes range from milliseconds to several hours.

    Research groups from many nations—Argentina, Bulgaria, China, the Czech Republic, Japan, Mexico, Russia, Slovakia, the United States, and others—are joining the field of HEAP research. Meanwhile, physicists from Armenia have been working on the detection of cosmic rays for many decades and focusing on intensive studies of TGEs for the past 10 years.

    Fig. 1. The origins of natural gamma radiation include the newly discovered long-lasting thunderstorm ground enhancements (TGEs). These enhancements consist of short emissions of high-energy electrons and gamma rays and hours-long emissions of radon-222 progenies lifted into the atmosphere by the thunderstorm’s electric field. Abbreviations are ArNM, Aragats Neutron Monitor; ASNT, Aragats Solar Neutron Telescope; CR, cosmic ray; EAS, extensive air shower; IC+, positive intracloud discharge; IC–, negative intracloud discharge; LPCR, lower positively charged region; NaI spectrometers, sodium iodide spectrometers; CUBE, Cube particle detector assembly; SEP, solar energetic particle; SEVAN, Space Environment Viewing and Analysis Network; and TGF, terrestrial gamma ray flash. Credit: Ashot A. Chilingarian

    Cosmic rays produced by high-energy astrophysics sources (ASPERA collaboration – AStroParticle ERAnet)

    Aragats Neutron Monitor.http://www.nmdb.eu

    Aragats Solar Neutron Telescope. https://www.researchgate.net/

    Observations from Aragats

    At the Nor-Amberd and Aragats research stations on the slopes of Mount Aragats, an isolated volcano massif in Armenia, numerous particle detectors have been continuously registering fluxes of charged and neutral particles for the past 75 years. At the main facility, the Aragats research station of the Yerevan Physics Institute’s CRD, the main topic of research is the physics of the high-energy cosmic rays accelerated in our galaxy and beyond. Surface arrays consisting of hundreds of plastic scintillators measure extensive air showers, the cascades of billions of particles born when primary high-energy protons or fully stripped nuclei originating outside our solar system interact with atoms in Earth’s atmosphere.

    The Aragats station is located on a flat volcanic highland 3,200 meters above sea level near Lake Kari, a large ice lake, and is especially well situated to record thunderstorm phenomena because the bases of thunderclouds are often very close to Earth’s surface. Electrons and gamma rays travel only a short distance through the atmosphere between the clouds and the particle detectors on the ground with very little, if any, attenuation.

    In 2008, during a quiet period of solar cycle 24, the CRD turned to investigations of high-energy phenomena in the atmosphere over the Aragats station. Since then, existing and newly designed particle detectors at the Aragats station have observed more than 500 TGE particle bursts—about 95% of the strongest TGEs recorded to date. (There have been only a few other reports of TGEs elsewhere [e.g., Enoto et al., 2017 Nature].) Aragats researchers recently published the first catalog of TGE events [Chilingarian et al., 2019a Scientific Reports].

    TGEs observed from Aragats consist not only of gamma rays but also of sizable enhancements of electrons and also, rarely, neutrons [Chilingarian et al., 2010 Physical Review D]. The relativistic runaway electron avalanches (RREAs) that produce these TGEs are believed to be a central engine initiating high-energy processes in thunderstorms. During the strongest thunderstorms on Mount Aragats, RREAs directly observed using scintillator arrays and simultaneous measurements of TGE electron and gamma ray energy spectra proved that RREAs are a robust and realistic mechanism for electron acceleration.

    Models and Discoveries

    Our research group at Aragats was a major contributor at the 2019 symposium. We gave five talks about our newly developed model of natural gamma radiation (NGR) and the enhanced radiation fluxes incident on Earth’s surface during thunderstorms [Chilingarian et al., 2019b (above)], which was a central topic of discussion at the meeting. This comprehensive model, along with observations of minutes-long fluxes of high-energy electrons and gamma rays from RREAs, helps clarify the mechanism of hours-long isotropic fluxes of low-energy gamma rays (<3 megaelectron volts) emitted by radon-222 progeny species.

    It has been known for many years that radon-222 progenies are the main source of low-energy gamma rays [see, e.g., Reuveni et al., 2017 Atmospheric Research]; however, the mechanism of abrupt enhancement of this radiation during thunderstorms was unknown. Experiments on Aragats, performed in 2019, proved that emanated radon progenies become airborne, immediately attach to dust and aerosol particles in the atmosphere, and are lifted by the near-surface electric field upward, providing isotropic radiation of low-energy gamma rays.

    NGR is one of the major geophysical parameters directly connected to cloud electrification and lightning initiation. Low-energy NGR (<3 megaelectron volts) is due to natural isotopic decay. Middle-energy NGR during thunderstorms comes from the newly discovered electron accelerators in the thunderclouds (50 megaelectron volts) is caused by solar accelerators and ionizing radiation coming from our galaxy and the universe (Figure 1, top right).

    The Aragats group also observed direct evidence of an RREA for the first time in the form of fluorescent light emitted during the development of electron–gamma ray cascades in the atmosphere, work we reported on at the symposium. This observation correlated well with the high-energy electron flux registered by surface particle detectors.

    Next, we proved that in the lower dipole (a transient positively charged region at the base of thunderclouds), electrons are accelerated to high energies, forming avalanches that reach Earth’s surface and initiate TGEs [Chilingarian et al., 2020 Atmospheric Research]. We also performed simulations of electron propagation in strong atmospheric electric fields, proving the origin of the runaway electron phenomenon.

    Shedding Light on Lightning

    Other attendees at the 2019 symposium presented reports on lightning initiation and its relation to particle fluxes originating in thunderclouds. They spoke of classifying lightning types according to which sensors detected the atmospheric discharges and according to parameters of particle fluxes (intensity, maximum energy, and percentage of flux decline) abruptly terminated by the lightning flash. Attendees also presented on remote sensing methods for studying thundercloud structure and atmospheric electric fields, as well as on the influence of atmospheric electric fields on extensive air showers and Čerenkov light emitted by rapidly moving subatomic particles.

    During an excursion to the Aragats research station, conference attendees visited new facilities for the detection of atmospheric discharges. These new facilities use interferometry to study the causes of lightning initiation, which remain enigmatic. The interferometer operating at this station registered more than 400 lightning flashes in 2019 synchronously with the detection of cosmic rays and a near-surface electric field—a powerful demonstration of this very new application. The conference visitors were convinced that the interferometer data on atmospheric discharges and the associated particle flux characteristic measurements will lead to a comprehensive model of lightning initiation coupled with particle flux propagation in thunderstorm atmospheres.


    Chilingarian, A., et al. (2010), Ground-based observations of thunderstorm-correlated fluxes of high-energy electrons, gamma rays, and neutrons, Phys. Rev. D, 82(4), 043009, https://doi.org/10.1103/PhysRevD.82.043009.

    Chilingarian, A., et al. (2018), Structures of the intracloud electric field supporting origin of long-lasting thunderstorm ground enhancements, Phys. Rev. D, 98(8), 082001, https://doi.org/10.1103/PhysRevD.98.082001.

    Chilingarian, A., et al. (2019a), Catalog of 2017 thunderstorm ground enhancement (TGE) events observed on Aragats, Sci. Rep., 9, 6253, https://doi.org/10.1038/s41598-019-42786-7.

    Chilingarian, A., et al. (2019b), Origin of enhanced gamma radiation in thunderclouds, Phys. Rev. Res., 1(3), 033167, https://doi.org/10.1103/PhysRevResearch.1.033167.

    Chilingarian, A., et al. (2020), Termination of thunderstorm-related bursts of energetic radiation and particles by inverted intracloud and hybrid lightning discharge, Atmos. Res., 233, 104713, https://doi.org/10.1016/j.atmosres.2019.104713.

    Enoto, T., et al. (2017), Photonuclear reactions triggered by lightning discharge, Nature, 551, 481–484, https://doi.org/10.1038/nature24630.

    Gurevich, A. V. (1961), On the theory of runaway electrons, Sov. Phys. JETP, 12, 904–912, jetp.ac.ru/cgi-bin/dn/e_012_05_0904.pdf.

    Reuveni, Y., et al. (2017), Ground level gamma-ray and electric field enhancements during disturbed weather: Combined signatures from convective clouds, lightning and rain, Atmos. Res., 196, 142–150, https://doi.org/10.1016/j.atmosres.2017.06.012.

    Wilson, C. T. R. (1925), The acceleration of β‐particles in strong electric fields such as those of thunderclouds, Math. Proc. Cambridge Philos. Soc., 22(4), 534–538, https://doi.org/10.1017/S0305004100003236.

    See the full article here .


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