Researchers from the Oden Institute and Jackson School of Geosciences have developed an improved model for planet-wide groundwater flow prediction on Mars that is not only more accurate but, according to its author, more elegant too.
Mars is believed to have collided with a huge astral entity around four billion years ago.
The Late Heavy Bombardment refers to a period where it is believed that a disproportionately large number of asteroids collided with Mercury, Venus, Earth and Mars. Many meteors and meteorites impacted Mars resulting in the large number of massive impact craters on the surface of the Red Planet. The event is also believed to have created its northern lowland—so large it’s visible from space—where a significant tract of Martian land appears to be literally sliced off.
This basin is also believed to have once contained a massive body of water. “Mars used to have a lot of water and it still has ice likely before this collision.” That’s Mohammad Afzal Shadab, a CSEM graduate student at the Oden Institute whose team developed a very simple mathematical formula for predicting just how high that groundwater table would have been. The study entitled: “Estimates of Martian Mean Recharge Rates from Analytic Groundwater Models” is advised by Marc Hesse and is pursued in collaboration with Eric Hiatt. It is a collaboration between the Oden Institute for Computational Engineering and Sciences, Jackson School of Geosciences, Institute for Geophysics and Center for Planetary Systems Habitability.
“Using curvilinear coordinates transformation and groundwater flow dynamics, we developed analytic solutions for a steady unconfined groundwater aquifer beneath the southern highlands of Noachian Mars (4 billion years ago),” Shadab said.
They also used the models to explore self-consistent combinations of recharge (rainfall or precipitation) and hydraulic conductivities.
While models have been developed in the past, scientists have been relying upon the more straightforward Cartesian mapping method. No, previous Martian cartographers were not flat-earthers. But these earlier simplified models, predominantly limited to Cartesian and cylindrical coordinates, were found to be way off the mark.
Notwithstanding that planets are spherical in shape, no one had, heretofore, incorporated a spherical coordinate. Why? Simply put, because it requires more complex mathematics. “We found that all the previously published estimates for recharge rates are orders of magnitude off from what early Mars could accommodate,” he added.
Interestingly, the more “complex” mathematical model was able to produce simpler analyses than previous simulations. “Simple is the wrong word to use. I would say more elegant,” he added. “And 3D simulations on a complicated geometry with craters and putative shorelines developed by my co-collaborators at the Jackson School support the model, showing the same behavior.”
So northern Mars is headless. But it also has very deep holes—an area known as the northern lowlands. There are also southern highlands—where higher, more mountainous ground dominates the landscape.
Shadab and the research team made a model for a hypothetical ocean in the northern lowlands that is connected, or “recharged,” by a groundwater aquifer across the whole southern highlands.
Ridges that criss-cross the icy surface of Jupiter’s moon Europa indicate there are shallow pockets of water beneath, boosting hopes in the search for extra-terrestrial life, scientists said Tuesday.
Europa has long been a candidate for finding life in our solar system due to its vast ocean, which is widely thought to contain liquid water—a key ingredient for life.
There is a problem: the ocean is predicted to be buried 25-30 kilometers (15-17 miles) beneath the moon’s icy shell.
However water could be closer to the surface than previously thought, according to new research published in the journal Nature Communications.
The finding came partly by chance, when geophysicists studying an ice sheet in Greenland watched a presentation about Europa and spotted a feature they recognized.
“We were working on something totally different related to climate change and its impact on the surface of Greenland when we saw these tiny double ridges,” said the study’s senior author Dustin Schroeder, a geophysics professor at Stanford University.
They realized that the M-shaped icy crests on Greenland looked like smaller versions of double ridges on Europa, which are the most common feature on the moon.
Europa’s double ridges were first photographed by NASA’s Galileo spacecraft in the 1990s, but little was known about how they were formed.
The scientists used ice-penetrating radar to observe that Greenland’s ridges were formed when water pockets around 30 meters (100 feet) below the ice sheet‘s surface refroze and fractured.
“This is particularly exciting, because scientists have been studying double ridges on Europa for more than 20 years and have not yet come to a definitive answer for how double ridges form,” said lead study author Riley Culberg, an electrical engineering Ph.D. student at Stanford.
“This was the first time that we were able to watch something similar happen on Earth and actually observe the subsurface processes that led to the formation of the ridges,” he told AFP.
“If Europa’s double ridges also form in this way, it suggests that shallow water pockets must have been (or maybe still are) extremely common.”
‘Life has a shot’
Europa’s water pockets could be buried five kilometers beneath the moon’s ice shell—but that would still be much easier to access than the far deeper ocean.
“Particularly if such water pockets form because ocean water was forced up through fractures into the ice shell, then it’s possible that they would preserve evidence of any life in the ocean itself,” Culberg said.
Water closer to the surface would also contain “interesting chemicals” from space and other moons, increasing the “possibility that life has a shot,” Schroeder said in a statement.
We may not have too long to wait to find out more.
NASA’s Europa Clipper mission, scheduled to launch in 2024 and arrive in 2030, will have ice-penetrating radar equipment similar to that used by the scientists studying Greenland’s double ridges.
The spacecraft is unlikely to find definitive proof of life because it will not land on Europa, instead flying by and analyzing it.
But hopes remain high. The moon’s ocean is predicted to have more water than all of Earth’s seas combined, according to the Europa Clipper’s website.
“If there is life in Europa, it almost certainly was completely independent from the origin of life on Earth… that would mean the origin of life must be pretty easy throughout the galaxy and beyond,” project scientist Robert Pappalardo said on the website.
Water resource availability is the major limiting factor for sustainable development in drylands. The drylands of northern China contain only 19% of the country’s total water resources but house one-third of the national population, and are therefore under considerable water stress. In particular, Inner Mongolia, which is a typical dryland province, plays an important role in maintaining ecological security in northern China. For the past few years, its anthropogenic water consumption has increased 4-fold, from 6.68 billion m3 in 1987 to 27.11 billion m3 in 2015; this increase has seriously threatened regional grasslands, which also rely on water resources to sustain ecological integrity. The conflict between ecological and social-economic systems and the actions that might relieve it has been long overlooked, thus, might lead to unexpected problems when adopting one-sided policies.
Climate change intensifies the conflicting water demands between people and the environment and highlights the importance of effective water resource management for achieving a balance between economic development and environmental protection. In 2008, Inner Mongolia proposed strict regulations on water exploitation and utilization aimed at achieving sustainable development. By adopting these regulations, Inner Mongolia’s government aims to limit high water consumption and the expansion of polluting industries; by doing so, they aim to achieve industrial restructuring toward sustainable development. However, no systematic evaluation has been conducted to determine if and how such strict regulations on water conservation might alleviate the tension between environmental protection and economic development. Without this information, policy adjustment and the ability to achieve sustainable development are limited.
Now, a research group from University of Chinese Academy of Sciences studied the effectiveness and performance of these long-standing water conservation regulations. The results were published in Frontiers of Environmental Science & Engineering.
They found that the regulations drove industrial transformation, evidenced by the decreasing proportion of environmentally harmful industries such as coal and steel, and the increasing proportion of tertiary industries (especially tourism). Following industrial transformation, economic development decoupled from industrial water consumption and subsequently led to reduced negative environmental impacts.
Based on these results, adaptive strategies were developed for 12 cities by revealing and integrating their development pathways and relative status in achieving sustainable development. Integration and cooperation between cities were proposed, e.g., a water trade agreement between eastern Inner Mongolia (an economically underdeveloped region with relatively abundant water resources) and central Inner Mongolia (an economically developed region with high water stress). Such an agreement may enable the holistic achievement of sustainable development across regions. By integrating the findings of the research, a reproducible framework is established for water-management-based sustainable development strategies in drylands.
Stimulating the internal motivation of industrial transformation through the regulations of water resources could help achieve synergy between economic development and environmental protection, therefore, promoting sustainable development in drylands. Taken together, three suggestions are proposed for sustainable development in drylands: (1) restrict the water exploitation and regulate the water cost to reconcile the conflict between economy and environment; (2) promote novel technologies to increase the water use efficiency; (3) enhance regional cooperation achieve holistic development in a mutually beneficial way.
Yali Liu et al, Water resource conservation promotes synergy between economy and environment in China’s northern drylands, Frontiers of Environmental Science & Engineering (2021). DOI: 10.1007/s11783-021-1462-y
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Conflicts over water are as old as history itself, but the massive Google data centers on the edge of this Oregon town on the Columbia River represent an emerging 21st century concern.
Now a critical part of modern computing, data centers help people stream movies on Netflix, conduct transactions on PayPal, post updates on Facebook, store trillions of photos and more. But a single facility can also churn through millions of gallons of water per day to keep hot-running equipment cool.
Google wants to build at least two more data centers in The Dalles, worrying some residents who fear there eventually won’t be enough water for everyone—including for area farms and fruit orchards, which are by far the biggest users.
Across the United States, there has been some mild pushback as tech companies build and expand data centers—conflicts likely to grow as water becomes a more precious resource amid the threat of climate change and as the demand for cloud computing grows. Some tech giants have been using cutting-edge research and development to find less impactful cooling methods, but there are those who say the companies can still do more to be environmentally sustainable.
The concerns are understandable in The Dalles, the seat of Wasco County, which is suffering extreme and exceptional drought, according to the U.S. Drought Monitor. The region last summer endured its hottest days on record, reaching 118 degrees Fahrenheit (48 Celsius) in The Dalles.
The Dalles is adjacent to the the mighty Columbia River, but the new data centers wouldn’t be able to use that water and instead would have to take water from rivers and groundwater that has gone through the city’s water treatment plant.
However, the snowpack in the nearby Cascade Range that feeds the aquifers varies wildly year-to-year and glaciers are melting. Most aquifers in north-central Oregon are declining, according to the U.S. Geological Survey Groundwater Resources Program.
Adding to the unease: The 15,000 town residents don’t know how much water the proposed data centers will use, because Google calls it a trade secret. Even the town councilors, who are scheduled to vote on the proposal on Nov. 8, had to wait until this week to find out.
Dave Anderson, public works director for The Dalles, said Google obtained the rights to 3.9 million gallons of water per day when it purchased land formerly home to an aluminum smelter. Google is requesting less water for the new data centers than that amount and would transfer those rights to the city, Anderson said.
“The city comes out ahead,” he said.
For its part, Google said it’s “committed to the long-term health of the county’s economy and natural resources.”
“We’re excited that we’re continuing conversations with local officials on an agreement that allows us to keep growing while also supporting the community,” Google said, adding that the expansion proposal includes a potential aquifer program to store water and increase supply during drier periods.
The U.S. hosts 30% of the world’s data centers, more than any other country. Some data centers are trying to become more efficient in water consumption, for example by recycling the same water several times through a center before discharging it. Google even uses treated sewage water, instead of using drinking water as many data centers do, to cool its facility in Douglas County, Georgia.
Facebook’s first data center took advantage of the cold high-desert air in Prineville, Oregon, to chill its servers, and went a step further when it built a center in Lulea, Sweden, near the Arctic Circle.
Microsoft even placed a small data center, enclosed in what looks like a giant cigar, on the seafloor off Scotland. After retrieving the barnacle-encrusted container last year after two years, company employees saw improvement in overall reliability because the servers weren’t subjected to temperature fluctuations and corrosion from oxygen and humidity. Team leader Ben Cutler said the experiment shows data centers can be kept cool without tapping freshwater resources.
A study published in May by researchers at Virginia Tech and Lawrence Berkeley National Laboratory showed one-fifth of data centers rely on water from moderately to highly stressed watersheds.
Tech companies typically consider tax breaks and availability of cheap electricity and land when placing data centers, said study co-author Landon Marston, assistant professor of civil and environmental engineering at Virginia Tech.
They need to consider water impacts more seriously, and put the facilities in regions where they can be better sustained, both for the good of the environment and their own bottom line, Marston said.
“It’s also a risk and resilience issue that data centers and their operators need to face, because the drought that we’re seeing in the West is expected to get worse,” Marston said.
About an hour’s drive east of The Dalles, Amazon is giving back some of the water its massive data centers use. Amazon’s sprawling campuses, spread between Boardman and Umatilla, Oregon, butt up against farmland, a cheese factory and neighborhoods. Like many data centers, they use water primarily in summer, with the servers being air-cooled the rest of the year.
About two-thirds of the water Amazon uses evaporates. The rest is treated and sent to irrigation canals that feed crops and pastures.
Umatilla City Manager Dave Stockdale appreciates that farms and ranches are getting that water, since the main issue the city had as Amazon’s facilities grew was that the city water treatment plant couldn’t have handled the data centers’ discharge.
John DeVoe, executive director of WaterWatch of Oregon, which seeks reform of water laws to protect and restore rivers, criticized it as a “corporate feel good tactic.”
“Does it actually mitigate for any harm of the server farm’s actual use of water on other interests who may also be using the same source water, like the environment, fish and wildlife?” DeVoe said.
Adam Selipsky, CEO of Amazon Web Services, insists that Amazon feels a sense of responsibility for its impacts.
“We have intentionally been very conscious about water usage in any of these projects,” he said, adding that the centers brought economic activity and jobs to the region.
Dawn Rasmussen, who lives on the outskirts of The Dalles, worries that her town is making a mistake in negotiating with Google, likening it to David versus Goliath.
She’s seen the level of her well-water drop year after year and worries sooner or later there won’t be enough for everyone.
“At the end of the day, if there’s not enough water, who’s going to win?” she asked.
Big tech data centers spark worry over scarce Western water (2021, October 22)
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NASA on Thursday launched an online platform with information on how much water evaporates into the atmosphere from plants, soils and other surfaces in the U.S. West, data it says could help water managers, farmers and state officials better manage resources in the parched region.
The platform, OpenET, uses satellite imagery from the Landsat program, a decades-long project of NASA and the U.S. Geological Survey that records human and natural impacts on Earth’s surface.
Specifically, it provides data for 17 Western states—down to the quarter-acre—on how much evapotranspiration has taken place. That’s the process by which moisture in leaves, soil and other surfaces evaporates into the air.
The West has been mired in drought for more than two decades. Scientists say human-caused climate change has intensified conditions. Water levels at key reservoirs on the Colorado River have fallen to historic lows alongside growing demand, prompting the federal government to declare water cuts for some states next year. A blazing summer and years of record-breaking wildfires have also zapped moisture from the ground.
Detailed information on soil moisture could help farmers and water managers better plan during dry conditions and reduce how much water is used for irrigation, NASA scientists said on a Thursday call with reporters.
“Farmers and water managers have not had consistent, timely data on one of the most important pieces of information for managing water, which is the amount of water that’s consumed by crops and other plants as they grow,” said Robyn Grimm, a water specialist with the Environmental Defense Fund, which helped NASA develop the tool alongside other environmental groups and Google.
“To date, that data has been expensive and fragmented,” she said.
Many large farms in dry areas, such as California’s Central Valley, already have years of experience using advanced data systems to measure evapotranspiration and other water metrics that influence their growing and harvesting seasons and watering schedules.
Cannon Michael runs an 11,000-acre (4,452 hectare) farm in Merced County, California, that produces tomatoes, melons, cotton and alfalfa. Michael said he looked at NASA’s new platform, but didn’t think it would provide any additional benefit for his farm.
“We closely monitor and understand our water use,” he said. “Our farm is 75% drip irrigation, and we have a very detailed scheduling and forecasting process already in place.”
Meanwhile, Colorado rancher Joe Stanko in Steamboat Springs had read about the new tool in a magazine. Her family grows hay for their cattle, and she said the platform could help them determine which fields need more water to replenish soil. It could also help them decide when to harvest hay.
NASA said the platform includes historical data dating back to 1984. In coming months, it will be updated to include information about precipitation rates with the same level of detail. Eventually, the tool will extend to other parts of the U.S., including areas around the Mississippi River and Appalachian region, scientists said.
Every day—up to thirty times a day, in fact—one of Mark Mason’s employees at Nature’s Reward Farms in Monterey County, California brings him the results of a soil test for discussion.
Mason supervises fertilizer and irrigation for the farm’s 5,000 acres along California’s Central Coast, which is nicknamed “America’s Salad Bowl” and is one of the most productive and diverse agricultural regions in the world. Those soil test results are key inputs for one of his newest tools: CropManage, which is operated by the University of California Cooperative Extension and uses data from NASA and other sources to create customized irrigation and fertilizer recommendations. In addition to satellite measurements of crop development, it gauges local weather, soil characteristics, and irrigation system efficiency.
“CropManage gives a recommendation back to the person that’s gone out and pulled the soil sample,” Mason explained. “He gets the results, then discusses that with me. I know what the field looks like, so I’ll take CropManage’s recommendations and make a decision based on what I know about the irrigation method, when it will be harvested, the soil type, how the crop looks, and the history of that ground for that time of year.”
If you ate a fruit, vegetable or nut today, chances are good that it came from a farm like Nature’s Reward Farms in California’s Central Coast, or from the nearby Central Valley. Covering more than 20,000 square miles in the Golden State, these regions are home to thousands of farms that grow hundreds of different crops, annually producing more than one-third of the United States’ vegetables and two-thirds of their fruits and nuts.
But central California doesn’t get much rain. Most of the Central Valley’s water comes from streams and reservoirs that capture mountain snowmelt and groundwater stored in porous deposits deep below the surface. These water sources face increasing pressures due to climate change, human use and natural variability, making water management a complex and evolving issue. Monitoring how much water is available to grow our groceries has never been more vital, and NASA’s Earth-observing satellites and partnership programs help farmers, water resource managers and policymakers monitor and allocate increasingly scarce water resources throughout their state.
Watching the water supply
In an ideal year, heavy snow falls in California’s mountain ranges and accumulates over the winter and spring. The snow acts as a natural reservoir, holding and releasing water gradually into rivers and streams as the weather warms in spring. From there, a system of aqueducts, canals and pipelines carries the water to drier regions of the state. Many farmers in the central parts of the state use this water to irrigate their crops, and also rely heavily on groundwater from wells.
But not every year is an ideal year. In 2021, for example, extreme heat and drought have continued to pummel the West. The winter’s below-average precipitation and exceptionally small snowfall evaporated quickly in high spring temperatures or melted and soaked into soils still parched from a dry autumn and winter. As a result, little water remained to fill reservoirs and nourish plants further down the valley. Already tightly allocated, water supplies in the region have become even more scarce, and some farmers must make hard decisions on which crops will get that water.
NASA researchers closely observe central California’s water sources, how they’re changing over time, and why—and produce information that can be used to determine what to do about it. Satellites, airborne and field missions track snowfall, rainfall, soil moisture levels, groundwater depletion, crop health and evapotranspiration. By providing better information on the quantity of water entering and leaving the system these indicators help farmers determine how much water they will need and how much will be accessible.
Matt Rodell is the associate deputy director of Earth sciences for hydrosphere, biosphere, and geophysics at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. He studies groundwater around the world, using data from NASA’s Gravity Recovery and Climate Experiment Follow-On (GRACE-FO) mission. Groundwater is especially important in places like the Central Valley and Central Coast that don’t get much precipitation and face frequent droughts.
“Groundwater is hugely important because it’s typically always available,” Rodell said. “It’s stored up over many years, or decades, or centuries, or millennia—it’s like your savings account. You always want to have that water set aside so it’s there for hard times.”
California is one of the global hotspots GRACE researchers are studying. It’s one of many areas where groundwater is being depleted more quickly than it’s being recharged.
“People become overly reliant on groundwater,” Rodell said. “Ideally, like your savings account, you’d want to spend less than you invest in it over the long period. But in California, they use so much groundwater that the level has been declining for decades now.”
California recently passed its first statewide groundwater regulation policy, partly in response to groundwater depletion concerns, said Claudia Faunt, a hydrologist at the U.S. Geological Survey and program chief for the groundwater availability and use section at the USGS California Water Science Center in San Diego, California. In some areas, falling groundwater levels lead to subsidence: The land surface sinks as water is extracted from the deposits beneath, and these deposits settle and compact.
“Subsidence issues affect other parts of the infrastructure, and wells are going dry in areas when the water levels have been drawn down,” Faunt said. Drilling deeper when a well runs dry, or drilling new wells in search of water, is expensive and can contribute to even more groundwater depletion.
Other threats to the region’s water supply—like the declining snowpack and changing winter precipitation patterns—are driven by climate change. Also, warming climate will increase evapotranspiration, which contributes to soil moisture deficits and plant water stress, and can affect local weather. As precipitation patterns change, future rainfall scenarios could become increasingly extreme. In California and other parts of the western United States, this will likely look like drought, threatening food production.
Putting NASA data to work for california farmers
To cope with changing conditions, California farmers are looking to new tools and technologies to help them produce the fruits, nuts and vegetables in constant demand by U.S. consumers.
In addition to GRACE-FO studying groundwater, missions like SMAP (Soil Moisture Active Passive) and MODIS (Moderate Resolution Imaging Spectroradiometer) measure soil moisture and evapotranspiration, and GPM (the Global Precipitation Measurement mission) tracks rain and snowfall. The workhorse Landsat program, a joint effort of NASA and the U.S. Geological Survey, has measured crop health and growth for nearly 50 years. Furthermore, NASA collaborates with universities, private companies, research institutions and other government agencies to create tools and programs that put all this data to work. Through NASA Applied Sciences and its Food Security and Agriculture programs, including NASA Harvest, farmers can access usable information to make better decisions on their farms.
Lee Johnson is a senior research scientist at NASA’s Ames Research Center and California State University at Monterey Bay (CSUMB). In partnership with Forrest Melton of NASA’s Applied Sciences program and Alberto Guzman and Will Carrara of NASA Ames, he supports the Satellite Irrigation Management Support (SIMS) system, an online data platform that uses publicly available Earth satellite data and open-source models to map evapotranspiration at the quarter-acre scale.
“Evapotranspiration is a really big part of the hydrologic cycle, and yet in the past, a lot of information on it has been difficult to get or expensive,” Johnson said. “Everyone knows about precipitation; it’s on the home screen of your phone. But evapotranspiration is kind of the reverse process. For growers who want to use it to guide their crop production, this information has been scarce. And if you can’t reliably measure it, it’s harder to manage it.”
“For most crops, evapotranspiration represents the minimum amount of water that has to be replaced through irrigation or precipitation to maintain a healthy crop and maximize crop yields,” said Melton. “Linking satellite-based data from SIMS with CropManage helps farmers like Mark Mason and his team at Nature’s Reward take the guesswork out of estimating the irrigation and fertilizer needs for their crops.”
Another water management tool, GRAPEX (Grape Remote-sensing Atmospheric Profile and Evapotranspiration eXperiment), also uses Landsat data, this time to help vineyard owners. Thermal and visual Landsat images give growers information about their vineyards’ evapotranspiration and plant health and help them make sure they don’t get too wet or too dry.
“The goal of our work is to find ways to put NASA data into the hands of farmers and irrigators in the field, where it can help improve the sustainability of California agriculture,” said Guzman, a senior software engineer at NASA Ames and CSUMB who began his career working in the fields of California. “Partnerships with innovative producers like Nature’s Reward are the key to ensuring that we can take petabytes of satellite data and turn it into information that can be used for day-to-day decision making.”
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There isn’t much in Kamchatka, a remote peninsula in northeastern Russia just across the Bering Sea from Alaska, besides an impressive population of brown bears and the most explosive volcano in the world.
Kamchatka’s Shiveluch volcano has had more than 40 violent eruptions over the last 10,000 years. The last gigantic blast occurred in 1964, creating a new crater and covering an area of nearly 100 square kilometers with pyroclastic flows. But Shiveluch is actually currently erupting, as it has been for over 20 years. So why would anyone risk venturing too close?
Researchers from Washington University in St. Louis, including Michael Krawczynski, assistant professor of earth and planetary sciences in Arts & Sciences and graduate student Andrea Goltz, brave the harsh conditions on Kamchatka because understanding what makes Shiveluch tick could help scientists understand the global water cycle and gain insights into the plumbing systems of other volcanoes.
In a recent study published in the journal Contributions to Mineralogy and Petrology, researchers from the Krawczynski lab looked at small nodules of primitive magma that were erupted and preserved amid other materials.
“The minerals in these nodules retain the signatures of what was happening early in the magma’s evolution, deep in Earth’s crust,” said Goltz, the lead author of the paper.
The researchers found that the conditions inside Shiveluch include roughly 10%-14% water by weight (wt%). Most volcanoes have less than 1% water. For subduction zone volcanoes, the average is usually 4%, rarely exceeding 8 wt%, which is considered superhydrous.
Of particular interest is a mineral called amphibole, which acts as a proxy or fingerprint for high water content at known temperature and pressure. The unique chemistry of the mineral tells researchers how much water is present deep underneath Shiveluch.
“When you convert the chemistry of these two minerals, amphibole and olivine, into temperatures and water contents as we do in this paper, the results are remarkable both in terms of how much water and how low a temperature we’re recording,” Krawczynski said.
“The only way to get primitive, pristine materials at low temperatures is to add lots and lots of water,” he said. “Adding water to rock has the same effect as adding salt to ice; you’re lowering the melting point. In this case, there is so much water that the temperature is reduced to a point where amphiboles can crystallize.”
Andrea E. Goltz et al, Evidence for superhydrous primitive arc magmas from mafic enclaves at Shiveluch volcano, Kamchatka, Contributions to Mineralogy and Petrology (2020). DOI: 10.1007/s00410-020-01746-5
Wet and wild: There’s lots of water in the world’s most explosive volcano (2021, January 23)
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Jupiter’s moon Ganymede is the largest planetary satellite in the solar system. It’s also one of the most intriguing: Ganymede is the only moon with its own magnetic field, it is the most differentiated of all moons, and it likely possesses a subsurface ocean of liquid water. It was studied by the early Jupiter flybys made by the Pioneer and Voyager spacecraft, but our understanding today rests largely on observations made by NASA’s Galileo orbiter from 1995 to 2003.
Mura et al. now report some of the first in situ observations of Ganymede since the end of the Galileo mission. They used the Jovian Infrared Auroral Mapper (JIRAM) on board NASA’s Juno spacecraft to take images and spectra of the moon’s north polar region. On 26 December 2019, Juno passed Ganymede at a distance of about 100,000 kilometers, enabling JIRAM to map this region at a spatial resolution of up to 23 kilometers per pixel.
As Juno flies past Ganymede, the spacecraft can observe physical locations on the moon’s surface from a variety of angles. By comparing the brightness of these regions across a range of observation and illumination geometries, the authors developed a photometric model for Ganymede’s surface reflectance. They observed that wavelength-dependent reflectance relationships sometimes break down in the vicinity of relatively fresh craters, perhaps because of a larger average size of ice grains in these regions.
Combining their model with spectral observations of the 2-micrometer water ice absorption band allowed the authors to map the distribution of water ice in the north polar region. Where these estimates overlapped with maps derived from Earth-based telescopic observations, the researchers found largely good agreement. This congruence enabled them to extend the global water ice map for Ganymede to much more northerly latitudes.
Observations in other spectral bands also revealed the presence of nonwater chemical species on the surface of Ganymede, including possible detections of hydrated magnesium salts, ammonia, carbon dioxide, and a range of organic molecules.
A. Mura et al. Infrared Observations of Ganymede From the Jovian InfraRed Auroral Mapper on Juno, Journal of Geophysical Research: Planets (2020). DOI: 10.1029/2020JE006508