Groundwater levels are sinking ever faster around the world

Peer-Reviewed Publication

ETH ZURICH

 

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GROUNDWATER-​FED IRRIGATION BY AN ELECTRICITY-​OPERATED PUMP IN SOUTHWESTERN BANGLADESH.

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CREDIT: PHOTOGRAPH: AHMED ZIAUR RAHMAN

At the beginning of November, The New York Times ran the headline, “America is using up its groundwater like there’s no tomorrow.” The journalists from the renowned media outlet had published an investigation into the state of groundwater reserves in the United States. They came to the conclusion that the United States is pumping out too much groundwater.

But the US isn’t an isolated case. “The rest of the world is also squandering groundwater like there’s no tomorrow,” says Hansjörg Seybold, Senior Scientist in the Department of Environmental Systems Science at ETH Zurich. He is coauthor of a study that has just been published in the journal Nature.

Scientific evidence of rapidly depleting water resources

Together with researchers from the University of California, Santa Barbara (UCSB), he has corroborated the journalists’ worrying findings. It is not only in North America that far too much groundwater is being pumped out, but also in other parts of the world where humans have settled.

In an unprecedented feat of painstaking effort, the researchers have compiled and analysed data from over 170,000 groundwater monitoring wells and 1,700 groundwater systems over the past 40 years.

This measurement data shows that in recent decades, humans have massively expanded groundwater extraction worldwide. The water level in most groundwater-​bearing rock layers, known as aquifers, has fallen drastically almost everywhere in the world since 1980. And since 2000, this decline in groundwater reserves has accelerated. The effects are most pronounced in aquifers in the world’s arid regions, including California and the High Plains in the US, along with Spain, Iran, and Australia.

“We weren’t surprised that groundwater levels have fallen sharply worldwide, but we were shocked at how the pace has picked up in the past two decades,” Seybold says.

One of the reasons Seybold cites for the accelerated drop in groundwater levels in arid regions is that people use these areas intensively for agriculture and are pumping (too) much of the groundwater to the surface to irrigate crops, for example in California’s Central Valley.

Food cultivation and climate change exacerbate the problem

Moreover, the world’s population is growing, which means more food needs to be produced, for example in the arid regions of Iran. This is one of the countries where groundwater reserves have fallen the most.

But climate change is also exacerbating the groundwater crisis: some areas have become drier and hotter in recent decades, meaning agricultural crops need to be irrigated more heavily. Where climate change is driving a decline in precipitation, groundwater resources recover more slowly, if at all.

Heavy rainfall, which is occurring more frequently in some places as a result of climate change, is also not of any help. If the water comes in huge quantities, the soil often cannot absorb it. Instead, the water drains off at the surface without seeping into the groundwater. This problem is particularly acute in places with a high level of soil sealing, such as large cities.

Trend can be reversed

“The study also reveals good news,” says co-​author Debra Perrone. “Aquifers in some areas have recovered in places where there have been policy changes or where alternative sources of water are available for direct use or for recharging the aquifer.”

One of the positive examples is the Genevese aquifer, which supplies drinking water to around 700,000 people in the canton of Geneva and the neighbouring French department of Haute-​Savoie. Between 1960 and 1970, its level fell drastically because both Switzerland and France were pumping out water in an uncoordinated manner. Some wells even dried up and had to be closed.

To preserve the shared water resource, politicians and authorities in both countries agreed to replenish the aquifer artificially with water from the Arve River. The intention was first to stabilise the groundwater level and later to raise it – and the intervention was a success. “While the water level in this aquifer may not have returned to its original level, the example shows that groundwater levels don’t always have to go only one way: down,” Seybold says.

Other countries are reacting, too

The authorities have also had to take action in other countries: In Spain, a large pipeline has been built to carry water from the Pyrenees to central Spain, where it feeds the Los Arenales aquifer. In Arizona, water is diverted from the Colorado River into other bodies of water to replenish the groundwater reservoirs – although this does cause the delta of the Colorado River to dry up at times.

“Such examples are a ray of hope,” says UCSB researcher and lead author Scott Jasechko. Nevertheless, he and his colleagues are urgently calling for more measures to combat the depletion of groundwater supplies. “Once heavily depleted, aquifers in semi-​deserts and deserts may require hundreds of years to recover because there’s simply not enough rainfall to swiftly replenish these aquifers,” Jasechko says.

There is an additional danger on the coasts: if the groundwater level falls below a certain level, seawater can invade the aquifer. This salinises the wells, leaving the water that is pumped up unusable neither for drinking water nor for irrigating fields; trees whose roots reach into the flow of groundwater die. On the east coast of the US, there are already extensive ghost forests with not a single living tree.

“That’s why we can’t put the problem on the back burner,” Seybold says. “The world must take urgent action.”

The world has a problem: On all inhabited continents, groundwater resources whose levels have fallen to various degrees are marked by light to dark red zones.

CREDIT

(Illustrations: Scott Jasechko, UCSB)

JOURNAL

Nature

DOI

10.1038/s41586-​023-06879-8 

ARTICLE TITLE

Rapid groundwater declines in many aquifers globally but cases of recovery

ARTICLE PUBLICATION DATE

24-Jan-2024

Global groundwater depletion is accelerating, but is not inevitable

Aquifers are declining worldwide, put success stories highlight that proactive management can reverse these trends

Peer-Reviewed Publication

UNIVERSITY OF CALIFORNIA - SANTA BARBARA

 

IMAGE: 

THIS PAPER PROVIDES THE MOST COMPREHENSIVE ACCOUNT YET OF TRENDS IN GROUNDWATER LEVELS AROUND THE WORLD. DARKER COLORS INDICATE CHANGES OF 10 CM/YEAR OR MORE.

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CREDIT: JASECHKO ET AL.

(Santa Barbara, Calif.) — Groundwater is rapidly declining across the globe, often at accelerating rates. Writing in the journal Nature, UC Santa Barbara researchers present the largest assessment of groundwater levels around the world, spanning nearly 1,700 aquifers. In addition to raising the alarm over declining water resources, the work offers instructive examples of where things are going well, and how groundwater depletion can be solved. The study is a boon for scientists, policy makers and resource managers working to understand global groundwater dynamics.

“This study was driven by curiosity. We wanted to better understand the state of global groundwater by wrangling millions of groundwater level measurements,” said lead author Debra Perrone, an associate professor in UC Santa Barbara’s Environmental Studies Program.

The team compiled data from national and subnational records and the work of other agencies. The study took three years, two of which were spent just cleaning and sorting data. That’s what it takes to make sense of 300 million water level measurements from 1.5 million wells over the past 100 years.

Next came the task of translating the deluge of data into actual insights about global groundwater trends. The researchers then scoured over 1,200 publications to reconstruct aquifer boundaries in the regions of inquiry and evaluate groundwater level trends in 1,693 aquifers.

Their findings provide the most comprehensive analysis of global groundwater levels to date, and demonstrate the prevalence of groundwater depletion. The work revealed that groundwater is dropping in 71% of the aquifers. And this depletion is accelerating in many places: the rates of groundwater decline in the 1980s and ’90s sped up from 2000 to the present, highlighting how a bad problem became even worse. The accelerating declines are occurring in nearly three times as many places as they would expect by chance.

Groundwater deepening is more common in drier climates, with accelerated decline especially prevalent in arid and semi-arid lands under cultivation — “an intuitive finding,” said co-lead author Scott Jasechko, an associate professor in the university’s Bren School of Environmental Science & Management. “But it’s one thing for something to be intuitive. It’s quite another to show that it’s happening with real-world data.”

On the other hand, there are places where levels have stabilized or recovered. Groundwater declines of the 1980s and ’90s reversed in 16% of the aquifer systems the authors had historical data for. However, these cases are only half as common as would be expected by chance.

“This study shows that humans can turn things around with deliberate, concentrated efforts,” Jasechko said.

Take Tucson, Arizona for instance. Water allotted from the Colorado River is used to replenish the aquifer in the nearby Avra Valley. The project stores water for future use. “Groundwater is often viewed as a bank account for water,” Jasechko explained. “Intentionally refilling aquifers allows us to store that water until a time of need.” 

Communities can spend a lot of money building infrastructure to hold water above ground. But if you have the right geology, you can store vast quantities of water underground, which is much cheaper, less disruptive and less dangerous. The stored groundwater can also benefit the region’s ecology. In fact, while preparing a research brief in 2014, Perrone found that aquifer recharge can store six times more water per dollar than surface reservoirs.

Tucson’s groundwater recharge is a boon for the local aquifer; however, withdrawals have caused the mighty river to dwindle above ground. The Colorado rarely reaches its delta in the California Gulf anymore. “These groundwater interventions can have tradeoffs,” Jasechko acknowledged.

Another option is to focus on reducing demand. Often this involves regulations, permitting and fees for groundwater use, Perrone explained. To this end, she is currently examining water law in the western U.S. to understand these diverse interventions. Regardless of whether it comes from supply or demand, aquifer recovery seemed to require intervention, the study revealed.

The authors complemented measurements from monitoring wells with data from the Gravity Recovery and Climate Experiment (GRACE). The GRACE mission consists of twin satellites that precisely measure the distance between them as they orbit the Earth. In this way, the crafts detect small fluctuations in the planet’s gravity, which can reveal the dynamics of aquifers at large scales.

“The beauty of GRACE is that it allows us to explore groundwater conditions where we don’t have in-situ data,” Perrone said. “Our assessment complements GRACE. Where we do have in-situ data, we can explore groundwater conditions locally, a crucial level of resolution when you’re managing depletion.” This local resolution is critical, as the authors found out, because adjacent aquifers can display different trends.

That said, groundwater level trends don’t present the whole picture. Even where aquifers remain stable, withdrawing groundwater can still affect nearby streams and surface water, causing them to leak into the subsurface, as Perrone and Jasechko detailed in another Nature paper in 2021. 

The authors also analyzed precipitation variability over the past four decades for 542 aquifers. They found that 90% of aquifers where declines were accelerating are in places where conditions have gotten drier over the last 40 years. These trends have likely reduced groundwater recharge and increased demand. On the other hand, climate variability can also enable groundwater to rebound where conditions become wetter.

This study of monitoring wells complements a paper Perrone and Jasechko released in 2021. That study represented the largest assessment of global groundwater wells, and made the cover of the journal Science. “The monitoring wells are telling us information about supply. And the groundwater wells are telling us information about demand,” Perrone said.

“Taken together, they allow us to understand which wells have run dry already, or are most likely to run dry if groundwater-level declines occur,” Jasechko added.

Perrone and Jasechko are now examining how groundwater levels vary over time in the context of climate change. Connecting these rates of change to the depths of actual wells will provide better predictions of where groundwater access is at risk.

“Groundwater depletion is not inevitable,” Jasechko said. Fine resolution, global studies will enable scientists and officials to understand the dynamics of this hidden resource.

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JOURNAL

Nature

DOI

10.1038/s41586-023-06879-8 

ARTICLE TITLE

Rapid groundwater declines in many aquifers globally but cases of recovery

ARTICLE PUBLICATION DATE

24-Jan-2024

 

Uncovering the secrets behind the silent flight of owls

Researchers investigate the aeroacoustic mechanisms that allow owls to fly silently using numerical simulations

Peer-Reviewed Publication

CHIBA UNIVERSITY

 

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THE MICRO-FRINGES ON OWL WINGS EFFECTIVELY SUPPRESS THE NOISE WHILE MAINTAINING THE AERODYNAMIC PERFORMANCE OF THE WINGS COMPARABLE TO THAT OF A WING WITHOUT THE FRINGES.

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CREDIT: HAO LIU FROM CHIBA UNIVERSITY

Owls are fascinating creatures that can fly silently through some of the quietest places. Their wings make no noise while flying, enabling them to accurately locate their prey using their exceptional hearing ability while remaining undetected. This unique ability depends on many factors and has long been a hot research subject.

Studies have found associations between the ability to fly silently and the presence of micro-fringes in owl wings. These trailing-edge (TE) fringes play a crucial role in suppressing the noise produced by wing flap-induced air movement. 

Studying these fringes can lead to the development of promising methods to reduce noise caused by fluid machinery. While many studies have evaluated these fringes using flat plates and airfoils, their exact mechanisms and effects on the interactions of feathers and the different wing features in real owl wings remained unknown.

To unravel the secrets of silent owl wings, Professor Hao Liu with his colleagues, including Dr. Jaixin Rong from the Graduate School of Engineering and Dr. Yajun Jiang and Dr. Masashi Murakami from the Graduate School of Science at Chiba University in Japan, investigated how TE fringes influence both the sound and aerodynamic performance of owl wings. 

When asked about the motivation behind their study, Prof. Liu says, “Despite many efforts by many researchers, exactly how owls achieve silent flight is still an open question. Understanding the precise role of TE fringes in their silent flight will enable us to apply them in developing practical low-noise fluid machinery.” Their findings were published in the journal Bioinspiration & Biomimetics on November 17, 2023.

To understand how owl wings work, the team constructed two three-dimensional models of a real owl wing—one with and the other without TE fringes—with all its geometric characteristics. They used these models to conduct fluid flow simulations that combined the methods of large eddy simulations and the Ffowcs-Williams-Hawkings analogy. The simulations were conducted at the speed of the gliding flight of approach of a real owl.
 
Simulations revealed that the TE fringes reduced the noise levels of owl wings, particularly at high angles of attack, and maintained aerodynamic performance comparable to owl wings without fringes. The team identified two complementary mechanisms through which the TE fringes influence airflow. First, the fringes reduce the fluctuations in airflow by breaking up the trailing edge vortices. Second, they reduce the flow interactions between feathers at the wingtips, thereby suppressing the shedding of wingtip vortices. Synergistically, these mechanisms enhance the effects of TE fringes, improving both aerodynamic force production and noise reduction.
 
Emphasizing the significance of these results, Prof. Liu says, “Our findings demonstrate the effect of complex interactions between the TE fringes and the various wing features, highlighting the validity of using these fringes for reducing noise in practical applications such as drones, wind turbines, propellers and even flying cars.”
 
Overall, this study deepens our understanding of the role of TE fringes in the silent flight of owls and can inspire biomimetic designs that could lead to the development of low-noise fluid machinery.

About Professor Hao Liu
Dr. Hao Liu is a Professor at the Graduate School of Engineering at Chiba University, Japan. Prof. Liu leads the Center for Aerial Intelligent Vehicles at Chiba University. He obtained his Ph.D. from Yokohama National University in 1992. Prof. Liu has over 600 publications and 11,200 citations to his name (Google Scholar). He is one of the world’s top 2% scientists, according to Stanford University (2023). His research interests include biomechanics, biomimetics, and bio-inspired engineering.

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JOURNAL

Bioinspiration & Biomimetics

DOI

10.1088/1748-3190/ad0aa9 

METHOD OF RESEARCH

Computational simulation/modeling

SUBJECT OF RESEARCH

Animals

ARTICLE TITLE

Trailing-edge fringes enable robust aerodynamic force production and noise suppression in an owl wing model

SPACE

James Webb Space Telescope reveals one of the most mysterious worlds in the universe might have a volcanic moon

Maiya Focht,Morgan McFall-Johnsen
Tue, January 23, 2024 

Astronomers using the James Webb Space Telescope discovered evidence of an aurora on a brown dwarf.

Typically, a key ingredient to produce aurora is high-energy particles from a star.

But this free-roaming world has no star, so scientists suspect a moon is shooting lava at it.

NEW ORLEANS — When astronomer Jackie Faherty peered into space using information from the James Webb Space Telescope, there was something she couldn't take her eyes off of.

Brown dwarf W1935, a world larger than Jupiter drifting alone in open space about 47 light-years from Earth, was letting off a methane signature unlike anything ever seen before.

Brown dwarfs are some of the most unusual and mysterious objects in space. They form like stars but don't grow massive enough to generate their own energy via nuclear fusion in their cores. For this reason, experts sometimes call them "failed stars."

Brown dwarf W1935 may have aurora at its poles created by a volcanic moon that's orbiting the failed star.NASA, ESA, CSA, and L. Hustak (STScI)

The astronomers expected to see methane gas in the atmospheres of the brown dwarfs they were studying, but they didn't expect that any of the objects would actually emit methane.

The methane emission in the data "was like a pebble in a shoe. I couldn't get rid of it. I could only focus on this one feature," Faherty, who works at the American Museum of Natural History, said in a presentation at the 243rd meeting of the American Astronomical Society.

Methane emissions were discovered in the atmosphere of a brown dwarf.

NASA, ESA, CSA, and L. Hustak (STScI)

It's the first time such a methane fingerprint has appeared on a brown dwarf, Faherty said.

"For your typical brown dwarf just traversing the galaxy in solitude, your brown dwarf is very mysterious. It does not want to give away any of its secrets," said Austin Rothermich, a graduate student at the City University of New York, who presented other research on brown dwarfs at the conference.

But that methane hint may have given away one of this brown dwarf's biggest secrets: a volcanically active moon in its orbit.
Jupiter and Saturn offer clues


Aurora on Jupiter's north pole.NASA, ESA, and J. Nichols (University of Leicester)

It turns out methane emissions, similar to those observed on W1935, are also found on Jupiter and Saturn.

On those two planets, the methane emissions are linked to aurora — the dancing lights that appear when charged particles from the sun interact with the planets' magnetic fields and atmospheres.

On Earth, the aurora is also called the northern lights.

Faherty and her team concluded that this unusual brown dwarf likely hosts aurora, too.

Northern lights, also called aurora borealis, dance in the sky over Tromso, Norway.NTB/Rune Stoltz Bertinussen/Reuters

But the mystery didn't end there.

Typically, to produce an aurora you need a nearby star. But there is no nearby star to W1935. So what was supplying the high-energy particles to power its aurora?

An animation of the solar wind shows particles streaming from the sun towards Earth.NASA

Faherty and her team suspected a different kind of companion could be at work: an active moon.

Both Jupiter and Saturn have active moons that regularly eject material into space. Jupiter's moon Io erupts lava material into space while Saturn's Enceladus ejects geysers. Both types of material contribute to the two planets' auroras, and that's what could be happening with W1935, too.

"That does not mean that we're declaring that we have found an active moon, but it's one of the explanations," Faherty said.

Other possible solutions the team is exploring include free-floating matter in space, called interstellar plasma.

Whatever the reason may be, it takes very sensitive tools to detect brown dwarfs in the first place. So arriving at these conclusions would not have been possible without Webb, Faherty said.

"I don't think I emphasized this enough, these are so stinking faint. So faint. JWST was an absolute requirement to measure this," Faherty said.

Albedo closes $35M at boosted valuation to build satellites that orbit very, very close to Earth

Aria Alamalhodaei
Updated Tue, January 23, 2024 


Satellite startup Albedo aims to provide commercial orbital imagery so detailed that the military kept its own version under wraps — until it was leaked a few years ago by Donald Trump.

In 2019, then-president Trump tweeted a detailed image of a heavily damaged Iranian launch pad captured by a classified military satellite. The image, which was declassified in 2022, revealed what many in the commercial Earth observation industry suspected: that U.S. defense had the ability to capture images at a staggeringly sharp 10-centimeter resolution.

“When Trump tweeted a classified satellite image a few years ago that showed that we could capture 10-centimeter resolution from space, it sparked all this conversation in the commercial industry on how game-changing it would be to have that resolution commercially,” Albedo's co-founder and CEO Topher Haddad said in a recent interview. “I stumbled upon that conversation a while after it happened and basically couldn't get it out of my mind.”


At the time, Haddad was working on classified remote sensing satellites for the U.S. government at Lockheed Martin. A year later, Haddad teamed up with fellow Lockheed veteran AyJay Lasater and engineer Winston Tri to found Albedo, a company that’s aiming to do the impossible and deliver 10-centimeter resolution optical images to commercial customers at historically low costs.

(A 10-centimeter resolution essentially means that each pixel in an image covers an area the size of 10 centimeters by 10 centimeters on the ground. In comparison, the biggest optical imagery providers today collect images at a 30-centimeter resolution, which is algorithmically improved to 15 centimeters.)

Such low resolution, at a price the market will tolerate, is a big ask: The military satellites like the one that captured the image of the Iranian launch pad are widely believed to cost billions of dollars each. But Denver-based Albedo says it will be able to drive costs way, way down — not through big innovations on the optics side, but through its satellite bus platform that operates in very low Earth orbit (VLEO). That "is where the VLEO technology lives," Haddad said.

Instead of joining all the other Earth observation players and operating in low Earth orbit (LEO), the orbital band around Earth at an altitude of around 2,000 kilometers, Albedo is targeting the lesser-known (but aptly-named) VLEO that's between 250 and 450 kilometers. Albedo, which is almost entirely vertically integrated, has designed a satellite bus that is fully optimized for this environment: from the guidance, navigation and control (GNC) system; the robotics and software used to rapidly repoint the satellite and ensure images aren’t blurry; the solar arrays; and the mission planning and concept of operations to ensure that each satellite stays on orbit for an average of four years.

This last detail is key. While there are some upsides to operating in VLEO, like the fact that it’s less crowded and more protected from radiation, objects in that orbit are subject to a greater amount of atmospheric drag, since they are closer to Earth. But somewhat unintuitively, Albedo's satellites avoid this issue by being very dense and heavy, and by using an efficient electric propulsion system to counter the drag.

The biggest technical challenges, Haddad said, are actually in the robotics, control and attitude systems:

"There's three categories: there's stability, which is making sure your picture isn't blurry. There's agility, so being able to rapidly repoint at different targets that you're trying to image as you're passing over very quickly . . . And then there's accuracy, knowing exactly where you're pointed, which is related to [stability and agility] and also gives you that geolocation metric that certain customers care a lot about," Haddad explained.

“All those things at 10-centimeter resolution are just inherently very hard, because the angle from a single pixel is smaller than it would be for a 30-centimeter or 50-centimeter or three-meter. So any specific disturbance is going to impact the 10-centimeter pixel much more than a 30-centimeter pixel. Then you take that and you fly in VLEO, where the satellites are moving even faster around the Earth, there's torque from the atmosphere, all those things just pose an even harder challenge for GNC.”

Investors have rallied behind the company’s vision. In September 2022, a little less than a year after completing Y Combinator, Albedo announced it had raised a $48 million Series A round. Now the company says it has closed $35 million in Series A-1 financing, at an up-round valuation.

The use cases abound, from commercial to defense. Reflecting the dual-use nature of VLEO tech, Albedo’s investors include funds like Bill Gates’ Breakthrough Energy Ventures to defense tech-focused Shield Capital. This latest tranche was led by Standard Investments, the investing arm of industrial giant Standard Industries. New investors Booz Allen Ventures, Cubit Capital, and Bill Perkins also participated in this round, along with existing investors (like Breakthrough and Shield), as well as Initialized Capital, Y Combinator, Giant Step Capital, Republic Capital, and others. With this latest capital, the company’s raised $97 million to date.

Right now, Albedo is working toward launch of its first commercial satellite in the first half of 2025. Haddad declined to specify a timeline beyond that date but said that the company’s next goal would be to launch a block of six satellites that would provide a daily global revisit rate, and ultimately a full 24-bird constellation that would offer five revisits per day.

Atmospheric pressure changes could be driving Mars’ elusive methane pulses

Simulations will help Curiosity search for signs of past or present life on the Red Planet

Peer-Reviewed Publication

DOE/LOS ALAMOS NATIONAL LABORATORY

 

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NEW SIMULATIONS ARE HELPING INFORM THE CURIOSITY ROVER’S ONGOING SAMPLING CAMPAIGN.

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CREDIT: NASA/JPL-CALTECH/MSSS

New research shows that atmospheric pressure fluctuations that pull gases up from underground could be responsible for releasing subsurface methane into Mars’ atmosphere; knowing when and where to look for methane can help the Curiosity rover search for signs of life.

“Understanding Mars’ methane variations has been highlighted by NASA’s Curiosity team as the next key step towards figuring out where it comes from,” said John Ortiz, a graduate student at Los Alamos National Laboratory who led the research team. “There are several challenges associated with meeting that goal, and a big one is knowing what time of a given sol (Martian day) is best for Curiosity to perform an atmospheric sampling experiment.”

The paper was published the week of Jan. 22 in the Journal of Geophysical Research: Planets.

A primary focus of NASA’s Mars missions, including Curiosity and Perseverance, is to detect and understand past or present signs of life, such as methane. However, with the source of methane on Mars likely being underground, short-term variations in atmospheric methane levels have posed a research challenge.

To better understand Mars’ methane levels, Ortiz and his team used high-performance computing clusters to simulate how methane travels through networks of underground fractures and is released into the atmosphere, where it then mixes within the atmospheric column. They also modeled how methane is adsorbed onto the pores of rocks, which is a temperature-dependent process that may contribute to the methane level fluctuations.

Their simulations predicted methane pulses from the ground surface into the atmosphere just before the Martian sunrise in the planet’s northern summer season, which just recently ended. This corroborates previous rover data suggesting that methane levels fluctuated not only seasonally, but also daily.

This valuable data is helping inform the Curiosity rover’s ongoing sampling campaign.

“Our work suggests several key time windows for Curiosity to collect data. We think these offer the best chance of constraining the timing of methane fluctuations, and (hopefully) down the line bringing us closer to understanding where it comes from on Mars,” Ortiz said.

Paper: “Sub-diurnal methane variations on Mars driven by barometric pumping and planetary boundary layer evolution.” Journal of Geophysical Research: Planets. DOI: 10.1029/2023JE008043

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JOURNAL

Journal of Geophysical Research Planets

DOI

10.1029/2023JE008043 

METHOD OF RESEARCH

Computational simulation/modeling

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

Sub-Diurnal Methane Variations on Mars Driven by Barometric Pumping and Planetary Boundary Layer Evolution

ARTICLE PUBLICATION DATE

22-Jan-2024

Motion of satellite galaxies suggests younger universe

Peer-Reviewed Publication

CHINESE ACADEMY OF SCIENCES HEADQUARTERS

In standard cosmological models, the formation of cosmological structures begins with the emergence of small structures, which subsequently undergo hierarchical merging, leading to the formation of larger systems. As the Universe ages, massive galaxy groups and clusters, being the largest systems, tend to increase in mass and reach a more dynamically relaxed state.

The motions of satellite galaxies around these groups and clusters provide valuable insights into their assembly status. The observations of such motion offer crucial clues about the age of the Universe.

By using public data from the Sloan Digital Sky Survey (SDSS), a research team led by Prof. GUO Qi from the National Astronomical Observatories of the Chinese Academy of Sciences (NAOC) analyzed the kinematics of satellite pairs around massive galaxy groups. The team's findings suggest that the Universe may be younger than predicted by the LCDM model with Planck cosmological parameters.

This study was published in Nature Astronomy on Jan. 22.

The researchers investigated the movement of satellite pairs positioned on the opposite side of massive galaxy groups by using their velocity offsets from the central galaxy along the line of sight. They discovered a notable excess of pairs exhibiting correlated velocity offsets compared to pairs displaying anti-correlated velocity offsets.

"The excess of correlated satellite pairs suggests the presence of recently accreted or infalling satellite galaxies," said Prof. GUO Qi, the corresponding author of the paper.

This excess was also found in up-to-date cosmological simulations but the magnitude of this effect was considerably lower than in observations. The significant discrepancy between the observations and simulations implies that massive galaxy groups are younger in the real Universe.

"Since the age of the massive galaxy groups could be closely related to the age of the Universe, these findings consequently suggest a younger Universe compared to that derived from the cosmic microwave background (CMB) by the Planck Collaboration," said Dr. GU Qing, first author of the paper.

These findings present a challenge to the current cosmological model and may provide valuable insights into the Hubble tension problem.

This paper can be accessed at https://www.nature.com/articles/s41550-023-02192-6.

JOURNAL

Nature Astronomy

DOI

10.1038/s41550-023-02192-6 

ARTICLE TITLE

A younger Universe implied by satellite pair correlations from SDSS observations of massive galaxy groups

ARTICLE PUBLICATION DATE

22-Jan-2024

Successful failure: Sierra Space's inflatable habitat blows up as planned

Aria Alamalhodaei
Mon, January 22, 2024 



Sierra Space has completed a key test of its inflatable space habitat, as the company progresses toward launching and operating a private space station with Blue Origin before the end of the decade.

The “ultimate burst pressure” test of the inflatable module was conducted at NASA’s Marshall Space Flight Center. As the name suggests, the purpose of the test is to inflate the unit until it bursts. In this instance, engineers inflated the module to 77 psi before it burst, proving that it exceeded NASA’s recommended safety level of 60.8 psi by 27%.

While Sierra has conducted a series of burst tests on sub-scale units of the habitat, called Large Integrated Flexible Environment (LIFE), this is the first on a full-scale module. At full scale, the module stands at over 20 feet tall and is around one-third the volume of the International Space Station.


youtube https://www.youtube.com/watch?v=_7NiBD3KqkQ?si=emLD1Ci_8kzJqIg3

As Leanne Thompson, a systems engineer at Sierra, pointed out in a recent video on the test, it took NASA 10 to 15 launches to send up that same volume of habitable space with the ISS. Each LIFE module is designed to fit inside a standard five-meter payload fairing, though the company said it is working on bigger iterations of 1,400 cubic meters (larger than the ISS) that could fit in a seven-meter fairing.

The test focused on the LIFE habitat’s pressure shell or restraint layer, which is made of expandable “softgoods” that perform like a rigid structure once they’re inflated. Softgoods as a materials category have aerospace heritage: There have been inflatable airlocks attached to the ISS, and demonstration modules developed by Bigelow Aerospace were launched to space in the 2000s.

The softgoods that make up the LIFE habitat include Vectran straps, which are made out of high-performance polymers and other materials. In a press release, Sierra said that Vectran is “stronger than steel when inflated on-orbit.” The company is working with ILC Dover to design and test the straps prior to this full-scale test.

Although the burst test is certainly suggestive, it would be a mistake to compare the LIFE module to a balloon. In the video above, Sierra briefly displays nine layers that will ultimately make up each module, including the restraint layer, such as thermal insulation and an outer cover.

Sierra’s plan is to deploy the LIFE modules in low Earth orbit as part of Orbital Reef, a private space station the company is developing with Blue Origin. Notably, Sierra specifically references the project in the press release, which could be at least partly a response to reporting from CNBC last year that the Orbital Reef project was on the verge of falling apart.

Sierra said this year will be one of “aggressive” testing at both sub- and full-scale of the other layers of the habitat.

An impossibly huge ring of galaxies might lead us to new physics. Here's how

Keith Cooper
Mon, January 22, 2024 

A view of the sky with one dotted blue circle toward the top center and a dotted red art to the middle left.


An intergalactic ring-shaped superstructure of galaxies and galaxy clusters — so large it defies explanation — has been discovered. This is a structure that lives so deep in the universe that we see it as it was some 9.2 billion years ago.

The huge superstructure, nicknamed the "Big Ring," spans 1.3 billion light-years in diameter and has a circumference of about 4 billion light-years. It is also close to another immense superstructure, the "Giant Arc in the Sky," which is actually even larger with a diameter of 3.3 billion light-years. The Giant Arc sits at a similar distance to us in the constellation of Boötes, the Herdsman. Alas, these superstructures are far too faint to be seen with a backyard telescope.

In fact, both superstructures were discovered in observations performed by the 2.5-meter telescope of the Sloan Digital Sky Survey at Apache Point in New Mexico, U.S. by Alexia Lopez. Interestingly, Lopez, a Ph.D. student at the University of Central Lancashire in the U.K., spotted the galaxies in these superstructures not because they are bright, but rather because they absorb some of the light emanating from more distant quasars. Quasars are the extremely luminous interiors of active galaxies; they're powered by supermassive black holes.


"Identifying two extraordinary ultra-large structures in such close configuration raises the possibility that together they form an even more extraordinary cosmological system," said Lopez in a statement.

Related: Galaxy shapes can help identify wrinkles in space caused by the Big Bang

The Big Ring isn't actually even a ring – it's coiled sort of like a slinky. Plus, we see it edge-on.

Still, the problem with the Big Ring and the Giant Arc (and other similar superstructures, for that matter) is they defy cosmological theory.

According to theory, all structures in the universe can be traced back to what's known as the cosmic microwave background (CMB) radiation — the so-called "fireball of the Big Bang" that scientists observe filling the universe. During the first 300,000 years of cosmic history, the universe was a sea of dense plasma — that is, atomic nuclei and free electrons. Waves crashed through this plasma, with matter bunching up at the peaks and becoming more sparse in the troughs. Scientists call these waves baryonic acoustic oscillations, or BAOs.

However, after those 300,000 years, the temperature of the universe cooled sufficiently to allow atomic nuclei to soak up most of the electrons and form complete atoms. You might say that the cosmic plasma ocean "dried up"; cosmologists call it the "epoch of recombination." Without the electrons that constantly scattered photons, light was able to pass unhindered through the universe for the first time. This is what we detect as the CMB.

The CMB is mottled with subtle temperature variations that correspond to regions of greater and lesser density. This is the imprint of the final acoustic waves that rippled through the plasma before the epoch of recombination. The peaks of the waves mark what we describe today as the "cosmic web of matter," and it was at these peaks where galaxies, and galaxy clusters, began to form.

A graph with black dots strewn all over.

"One possibility is that the Big Ring could be related to baryonic acoustic oscillations," says Lopez. "[These] arise from oscillations in the early universe and today should appear, statistically at least, as spherical shells in the arrangement of galaxies. However, detailed analysis of the Big Ring revealed it is not really compatible with the BAO explanation: the Big Ring is too large and is not spherical."

Cosmological theory suggests that the largest structures — in the form of chains of galaxies and galaxy clusters — that BAOs could form should be, at most, 1.2 billion light-years in length. Yet, the circumference of the Big Ring and the length of the Giant Arc dwarf this constraint. To put into context how immense these superstructures are, the Giant Arc is one-fifteenth the radius of the whole, visible universe.

There are other huge superstructures in the universe too, such as the Sloan Great Wall, which is 1.37 billion light-years across and about a billion light years away from us. The South Pole Wall of galaxies is a more recently discovered structure; it's 1.4 billion light-years in length. Then there is the Clowes–Campusana LQG (co-discoverer Roger Clowes is also Lopez’s PhD advisor), which is a huge group of quasars spread across two billion light-years. We see these ancient quasars as they were some 9.5 billion years ago.

The Laniakea Supercluster, of which the Milky Way is a part, is tiny by comparison at just 520 million light-years across.

There are also hints of even larger structures; the "dark flow" represents the apparent motion of many galaxies in the visible universe. This motion seems to flow in a preferred direction, as though something over the cosmic horizon were pulling the galaxies one way. However, the strength of evidence for the dark flow is controversial, with some astronomers disputing its existence in general.

Nonetheless, these superstructures are so large that not only is it difficult to understand how they formed, but it's also hard to decode how they break the Cosmological Principle, a central tenet of the Standard Model of Cosmology. This principle states that, on large scales, the distribution of matter in the universe should be even and that no region should look substantially different from any other region. But clearly, the superstructures, and particularly the Big Ring and the Giant Arc, hugely stand out.

"Neither of these two ultra-large structures is easy to explain in our current understanding of the universe," said Lopez. "And their ultra-large sizes, distinctive shapes and cosmological proximity must surely be telling us something important — but what exactly?"

Related Stories:

— Life might have been possible just seconds after the Big Bang

— Bubble of galaxies spanning 1 billion light-years could be a fossil of the Big Bang

— Mysterious radio source in heart of ancient star cluster might be a rare black hole

One possibility is that the structures are hinting at exotic forms of currently known physics, or perhaps even new physics. For example the Nobel Laureate Sir Roger Penrose, who is a professor emeritus at the University of Oxford, has suggested a model called Conformal Cyclic Cosmology to describe a cyclical universe. Per this model, evidence for gravitational waves from previous eons of the universe could manifest as giant ring-shaped structures in the CMB. Penrose's model has not proven popular among cosmologists, but could the Big Ring and Giant Arc give it a worthy shot?

Another possibility is that the superstructures are evidence for cosmic strings, which are hypothetical one-dimensional defects in spacetime believed to have formed during the Big Bang. Cosmic strings could potentially stretch across billions of light-years, yet be narrower than the width of a proton. It has been suggested that if cosmic strings exist, they could affect the clustering of matter.

"The Big Ring and the Giant Arc, both individually and together, gives us a big cosmological mystery as we work to understand the universe and its development," concluded Lopez.

Lopez presented the findings at the 243rd meeting of the American Astronomical Society.

Discovering the physics behind 300-year-old firefighting methods

Smoothing out the pulses in pumped water was a gamechanger in the 1700s.

Peer-Reviewed Publication

AMERICAN INSTITUTE OF PHYSICS

 

IMAGE: 

THE 1725 NEWSHAM FIRE ENGINE INSPIRED THE AUTHORS TO EXAMINE THE WINDKESSEL EFFECT AND CAPTURE THE PHYSICS BEHIND THE ENDURING TECHNOLOGY OF A STEADY STREAM OF WATER UNDER PRESSURE.

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CREDIT: PHOTO USED COURTESY OF THE COLONIAL WILLIAMSBURG FOUNDATION. MUSEUM PURCHASE.

WASHINGTON, Jan. 23, 2024 – Today, water pressure technology is ubiquitous, and any person who showers, waters a garden, or fights fires is benefiting from the technology devised to harness it. In the 17th and 18th centuries, though, a steady stream of water not punctuated by pressure drops was a major breakthrough.

In 1666, when bucket brigades were the best line of defense, the Great Fire of London burned almost all of the city’s tightly packed, wooden structures. The disaster destroyed hundreds of thousands of homes and dozens of churches, demonstrating the need for better firefighting methods and equipment.

One landmark advancement was the invention “sucking worms,” leather hoses attached to manually operated pumps. Then came the Windkessel, a chamber in the bottom of a wooden wagon that compressed air to pump water continuously through a hose, creating a steady stream.

Inspired by a 1725 fire engine that pumped water at larger distances and higher speeds than previously possible, authors publishing in the American Journal of Physics, by AIP Publishing, analyzed the pressure chamber’s Windkessel effect to capture the physics behind this widely used, enduring technology.

“There are many fascinating physics problems hiding in plain sight within books and papers written centuries ago!” author Trevor Lipscombe said. “Recently we’ve been working on applying elementary fluid mechanics to biological systems, and came across a common description in medical journals: that the heart acts as a Windkessel. That begs the question of what, precisely, is a Windkessel? Following the trail, we found descriptions of Lofting’s ‘sucking worm’ device and, in Newsham’s fire engine, a lifesaving application.”

To pinpoint what factors are most influential in the Windkessel effect, the authors compared the initial state of the chamber, the rate at which bucket brigades could pour water in (volumetric inflow), the length of time pressure builds, and the effects on output flow rate.

“When faced with Lofting’s design, or the Newsham fire engine, a physicist wants to sort out the basic science involved – simply because it’s there,” Lipscombe said. “It’s the joy of doing physics. But also, there’s a pedagogical aspect. Our article builds a simple model that shows how a Newsham fire engine works. We’re partly answering the ‘when will I ever use this stuff?’ question.”

Next, the authors plan to examine the physiological Windkessel involved in the heart-aorta system. 

“Knowledge of Bernoulli’s law, the ideal gas law, and isothermal expansion are the three ingredients we baked into a model to explore how this device worked,” Lipscombe said. “But if we understand this system better, we could look at the parameters that are important and see how changing them might improve the device.”

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The article “From sucking worms to Windkessels: The physics of an early eighteenth-century firefighting device” is authored by Don S. Lemons and Trevor C. Lipscombe. It will appear in the American Journal of Physics on Jan. 23, 2024 (DOI: 10.1119/5.0147573). After that date, it can be accessed at https://doi.org/10.1119/5.0147573.

ABOUT THE JOURNAL

The American Journal of Physics is devoted to the instructional and cultural aspects of physics. The journal informs physics education globally with member subscriptions, institutional subscriptions, such as libraries and physics departments, and consortia agreements. It is geared to an advanced audience, primarily at the college level. Contents include novel approaches to laboratory and classroom instruction, insightful articles on topics in classical and modern physics, apparatus, and demonstration notes, historical or cultural topics, resource letters, research in physics education, and book reviews. See https://aapt.scitation.org/journal/ajp.

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JOURNAL

American Journal of Physics

DOI

10.1119/5.0147573 

ARTICLE TITLE

From sucking worms to Windkessels: The physics of an early eighteenth-century firefighting device

ARTICLE PUBLICATION DATE

23-Jan-2024