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An international research team led by the GEOMAR Helmholtz Center for Ocean Research Kiel has discovered a globally unique system on the seabed off the coast of Papua New Guinea. During their expedition aboard the research vessel SONNE, they came across the "Karambusel" field, where hydrothermal vents and methane seeps occur immediately adjacent to one another.

Hidden beneath the biggest ice mass on Earth, hundreds of subglacial lakes form a crucial part of Antarctica's icy structure, affecting the movement and stability of glaciers, and consequentially influencing global sea level rise.

Earlier in 2025, UNSW Sydney Ph.D. candidate Christina Schmidt submitted her thesis—from the deck of Australia's multi-billion-dollar icebreaker, just off the East Antarctic coast.

Every year, soils across Thailand are baked hard and bone-dry for months under the unrelenting tropical Sun. But once the long, hot buildup to the monsoon season comes to a head and the rains arrive—typically in May or June—the landscape transforms in a matter of weeks into a patchwork of verdant wetlands.

With this transformation comes a flurry of activity, because many of these wetlands are, in fact, rice paddies ready to be planted. Workers wade through the fields, scattering seed or planting seedlings one by one in the butter soft soil. Months later, as long as these plants have had adequate water and nutrients, they’ll be harvested for their all-important grains.

Rice paddies in Thailand and elsewhere are vital economically and for food security, with rice being the third-most-grown cereal commodity globally. They are also part of the worldwide system of wetlands. From rivers and lakes to marshlands and intertidal flats, wetlands are important ecological and geochemical systems because of the ecosystem services they provide: biodiversity, natural pollution remediation, carbon sequestration, and protection against storm surges, to name a few.

Worachart Wisawapipat of Kasetsart University checks the condition of the soil at a rice paddy experiment site in northeastern Thailand. Credit: Kurt Barmettler

Rice paddies are also of special interest to geochemists, because the regular seasonal pattern of flooding and drainage in many paddy fields makes them ideal natural laboratories in which to study soil biogeochemical processes. Indeed, in several locations in Thailand in 2021, scientists from the Swiss Federal Institute of Technology (ETH Zurich) and Kasetsart University in Bangkok joined the workers in the fields as the growing season began. The scientists were there to plant not rice, though, but iron minerals, with the purpose of testing a new method for investigating how cycles of wetting and drying contribute to these minerals’ reactivity in soil.

A Linchpin of Soil Functioning

Iron is a linchpin of chemical cycling in the environment.

Iron is usually among the most abundant elements in soils, and it is a linchpin of chemical cycling in the environment. It’s thus of critical interest to farmers concerned with the availability of nutrients to their plants, engineers determining risks posed by toxic elements in soil, and land managers wanting to understand soil carbon storage. For several reasons, iron more often than not significantly controls how soil nutrients and toxic elements behave, how carbon is stored, and how other chemical processes play out in soils.

One reason is that iron is reactive in a variety of environmental conditions. In contact with air, oxidized forms of iron—including the yellow-brown to orange oxyhydroxide minerals commonly recognized as rust—are most stable and abundant. When a soil is flooded and the flow of oxygen through it is restricted, some of these minerals may dissolve. This dissolution occurs because some microorganisms can use iron minerals as an alternative to oxygen in the reduction and oxidation (redox) reactions they rely on for energy. In other words, some microorganisms essentially breathe redox-active iron (see video below), reducing oxidized iron and converting it to other forms.

Iron is also very versatile and combines with many other chemical elements to form a wide variety of minerals such as oxyhydroxides, carbonates, phosphates, sulfides, hydroxysulfates, and others that can host trace elements in their structures. What’s more, iron mineral particles tend to be very small and have large surface areas that allow them to bind other compounds. This property also makes iron mineral particles susceptible to rapid change under evolving environmental conditions.

Following Mineral Transformations in Field Soils

Studying the behavior of iron in soils using measurement techniques that are not specific to iron is challenging. The relatively small signatures of iron minerals are often overshadowed by those of the much more abundant silicate minerals that make up the bulk of soil mass.

With techniques that do selectively detect iron in soil, such as synchrotron X-ray absorption spectroscopy, researchers can follow changes in the composition of a whole soil sample, but not changes in a single target mineral. And if the complexity of the surrounding soil is stripped away to perform simplified laboratory experiments focusing on iron minerals, the mineral transformations observed do not always reflect what happens in natural soils.

Katrin Schiedung of ETH Zurich takes soil samples in a flooded rice paddy in northeastern Thailand. Credit: Ruben Kretzschmar

Iron minerals enriched in iron-57 and having precisely controlled properties can be synthesized in the laboratory, then mixed into soils to undergo reactions similar to those of natural iron minerals.

To overcome the challenge of tracing iron mineral transformations in soil, we developed a new approach using a stable isotope of iron to label synthetic minerals. Iron-57 occurs naturally, making up about 2.1% of the iron in soils and exhibiting the same chemical behavior as other naturally occurring iron isotopes (iron-54, 5.8%; iron-56, 91.8%; iron-58, 0.3%). Iron minerals enriched in iron-57 and having precisely controlled properties can be synthesized in the laboratory, then mixed into soils to undergo reactions similar to those of natural iron minerals. Even if the experimental enrichment of iron in the soil is small, the iron-57 is predominantly present in the synthetic minerals, allowing us to focus specifically on what happens to those minerals.

We chose iron-57 as a tracer in our experiments because of the ability to analyze it using Mössbauer spectroscopy. This technique, based on Rudolf Mössbauer’s fortuitous (and 1961 Nobel Prize–winning) discovery of recoilless nuclear resonance fluorescence, is sensitive to the redox state and chemical environment around iron-57 atoms in a sample. Crucially, all other isotopes of iron are invisible using this technique.

Mössbauer spectroscopy has been widely used in the Earth sciences, including for mineralogical analyses of soil samples and Martian rocks. In our application, adding iron-57 minerals into soils and tracing them with Mössbauer spectroscopy allows us to follow otherwise hidden mineral transformations (Figure 1).

Fig. 1. In the newly developed method, iron-57-labeled (57Fe-labeled) synthetic minerals are used to enrich a natural soil sample, which is placed in a porous mesh bag so it can still interact chemically with the surrounding soil. Following the experiment, Mössbauer spectroscopy, which irradiates the sample with gamma rays of a frequency that interacts only with iron-57, is used to measure the transformation products of the labeled minerals.

After adding portions of synthetic jarosite (a potassium-iron hydroxysulfate) or ferrihydrite or lepidocrocite (both iron oxyhydroxides) to small plots in the Thai rice paddies early in the growing season, we went back several times until the end of the season 4 months later to collect soil samples for analysis.

The mineral transformations we observed with Mössbauer spectroscopy were dominated by the dissolution of the added minerals and the release of reduced iron into soil pore water. Proximity to bacteria in the soil promoted mineral dissolution, and some of the released iron either remained dissolved or was trapped on soil particles. New minerals that formed—including green rust, a highly reactive hydroxide mineral that is usually difficult to detect in the environment—tended to be nanocrystalline in size and often contained both reduced and oxidized forms of iron.

Joëlle Kubeneck of ETH Zurich removes a sediment core from the intertidal wetlands of Germany’s Wadden Sea. Credit: Ruben Kretzschmar

Such results can shed light on biogeochemical cycling that affects ecosystem processes. Dissolution of iron minerals might lead to releases of associated pollutants, nutrients, or carbon compounds, for example. On the other hand, we observed that many of the reaction products in soil are nanocrystalline minerals, which have large reactive surface areas that might adsorb dissolved compounds such as metals.

We have also applied this new approach to understand a range of iron mineral transformation processes in soil and sediment environments other than rice paddies. In sediments along Germany’s north coast, for example, we observed the in situ formation of vivianite, a reduced iron phosphate mineral, in a matter of weeks. Phosphorus in vivianite has limited bioavailability, so formation of the mineral can control the availability of phosphorus in the environment and potentially reduce the risk of eutrophication. In addition, we have used the method to study oxidation reactions of reduced iron minerals, sulfidization of vivianite and lepidocrocite leading to the formation of iron sulfide minerals like greigite, and interactions between iron and organic matter during redox cycles.

An Array of Applications

Iron minerals are ubiquitous in natural environments and are used in many engineering applications. We anticipate that iron-57 labeling of minerals coupled with Mössbauer spectroscopy, although applied only to soils so far, could help to answer questions about transformations of these minerals in other domains of the Earth sciences and beyond.

Using iron-57 tracers could contribute to studies on the origins of iron mineral assemblages in sedimentary deposits on Earth or other astronomical bodies such as Mars.

Using iron-57 tracers could, for example, contribute to studies on geological processes, including weathering or metamorphism, or on the origins of iron mineral assemblages in paleosols and other sedimentary deposits on Earth or other astronomical bodies such as Mars.

Experiments with iron-57-labeled minerals could also help to understand redox-driven iron mineral transformation processes at work in applied geoscience technologies. In pollution management, for example, permeable reactive barriers containing iron are a tool for mitigating the spread of contaminants in groundwater. Another example involves geological deposits of redox-active iron minerals that may be used to store or produce hydrogen as a clean energy source.

Outside the Earth sciences, potential applications of iron-57-labeled synthetic minerals exist in fields as diverse as corrosion science, construction engineering, and experimental archaeology. The formation of rust on iron-bearing objects is the outcome of many interrelated chemical processes. Iron-57 tracers may help to follow and unravel those corrosion processes. They could also probe effects of different metal alloy compositions and exposure environments in tests of the longevity of steel infrastructure or of conservation methods for historical artifacts.

For now, our findings from the synthetic iron minerals we’ve “planted” in rice paddy soils are shaping understanding of the chemistry of periodically flooded soils, revealing that just like plants, the life cycles of iron minerals depend on the composition of and conditions in the soil. With continuing research in soils and with new applications focused on other natural and engineered environments, scientists can gain needed insights into how iron in its many forms affects vital issues from soil health and pollution transport to carbon storage and energy production.

Acknowledgments

This research was carried out as part of the European Research Council–funded IRMIDYN (Iron Mineral Dynamics in Soils and Sediments) project at ETH Zurich. The research was led by Ruben Kretzschmar with team members Laurel ThomasArrigo, Katherine Rothwell, Luiza Notini, Katrin Schiedung (published as Katrin Schulz), Joëlle Kubeneck, Andrew Grigg, Pierre Lefebvre, Sara Martinengo, and Giulia Fantappiè, while each was affiliated with the Institute of Biogeochemistry and Pollutant Dynamics at ETH Zurich, in Switzerland. We acknowledge important contributions to the research made by Kurt Barmettler (ETH Zurich) and Worachart Wisawapipat (Kasetsart University).

Author Information

Andrew R. C. Grigg (andrew.grigg@usys.ethz.ch), Institute of Biogeochemistry and Pollutant Dynamics, ETH Zurich, Zurich, Switzerland; Katrin Schiedung, Thünen Institute, Braunschweig, Germany; Joëlle Kubeneck, TNO–Geological Survey of the Netherlands, Utrecht; also at Radboud University, Nijmegen, Netherlands; and Ruben Kretzschmar, Institute of Biogeochemistry and Pollutant Dynamics, ETH Zurich, Zurich, Switzerland

Citation: Grigg, A. R. C., K. Schiedung, J. Kubeneck, and R. Kretzschmar (2025), Tracing iron’s invisible transformations just beneath our feet, Eos, 106, https://doi.org/10.1029/2025EO250347. Published on 19 September 2025. Text © 2025. The authors. CC BY-NC-ND 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.

Two billion years ago, a massive star exploded. When its light reached Earth in 2021, it joined more than 20,000 recorded supernova candidates observed that year.

This one was unique, however. It exhibited features not shared by any other known stellar explosion: The star had shed almost all of its outer layers before it died, exposing a core rich in silicon and sulfur.

SN 2021yfj, as this supernova is labeled, revealed never before seen details about stellar interiors. Precisely how a star could die this way is a marvelous puzzle that may help researchers learn about the deaths of the most massive stars and how they spread new elements through the cosmos.

“By studying supernovae, we can develop ideas of how stars form, evolve, and die,” said Steve Schulze of Northwestern University in Illinois, who led the observations and analysis of SN 2021yfj, published in Nature.

Onions Have Layers, Stars Have Layers

All stars, including the Sun, spend the majority of their life cycles fusing hydrogen into helium in their cores, which are surrounded by a hydrogen plasma envelope. When this fuel is exhausted, the core contracts and begins fusing helium into carbon and oxygen. For the most massive stars (those at least 8 times the mass of the Sun) this process continues to fuse heavier and heavier elements in the core.

The result is an onion-like (or ogre-like) character of aging high-mass stars: a hydrogen envelope surrounding a shell of helium, around a shell of carbon and oxygen. Layers of neon, magnesium, silicon, sulfur, and higher-mass nuclei form deeper toward the core. Eventually the energy produced by fusion is no longer able to maintain the core’s integrity, at which point the star explodes as a supernova.

This is the story theory tells, at least; these shells aren’t visible to telescopes. Astronomers must deduce the makeup of interiors from the spectrum of light stars emit when they explode.

“The spectra of supernovae are their fingerprints.”

“The spectra of supernovae are their fingerprints,” said Maryam Modjaz, an astronomer at the University of Virginia who was not involved in the study. She called this type of research stellar forensics. “We see the explosion of the star and we work backwards.”

However, very massive stars shed a great deal of their outer envelopes long before they explode, as astronomers observed during the dramatic dimming of Betelgeuse in 2019. Some extremely massive specimens known as Wolf-Rayet (pronounced “rah-YAY”) stars expel their envelopes much earlier in their lifetimes. The most commonly observed type of Wolf-Rayet stars consist of a hydrogen nebula swathing the extremely hot layers surrounding the core, which is dominated by emissions from helium and carbon.

I Like That Spectrum—That Is a Nice Spectrum

SN 2021yfj took this early-shedding process further than any other star yet observed: It had shed not only its hydrogen envelope, but also its helium, carbon, and oxygen shells. The spectrum Schulze and his colleagues measured exhibited emissions from ionized silicon and sulfur, indicating the progenitor had ejected that layer before exploding.

“The progenitor star [of supernova 2021yfj] had essentially lost almost all of its shells,” Schulze said. Astronomers have observed other stars that have been stripped of their outer layers, but never to this extreme.

“We have spectra from hundreds of thousands of supernovae, [and] this is the first time we’ve seen deep into the guts of a dying star.”

Though that provided strong evidence supporting the onion model for high-mass stars, it also was surprising: Nobody expected a star to shed that much material before going supernova.

“We have spectra from hundreds of thousands of supernovae, [and] this is the first time we’ve seen deep into the guts of a dying star,” Modjaz said. “This must be a very unique, very uncommon explosion and therefore [uncommon] progenitor.”

“The properties of supernova 2021yfj are so extreme that it’s challenging to find a model that can describe all of the observations,” Schulze said.

“Our leading hypothesis or leading idea,” he continued, “is that it was a very massive star, around 60 times more mass than the Sun.” Because it had already shed its hydrogen and helium by the time it was observed, though, the star was probably even more massive when it was born. He cautioned against trying to make too many guesses based on the data so far. “Exactly how massive it was will require very detailed simulations [and] the development of models that don’t exist yet.”

Schulze noted that even with hundreds of thousands of identified supernovae, astronomers have yet to see all the possible types. To make things more challenging, supernovae—bright as they are—are single points of light that fade over a matter of days, so spotting them often involves a degree of luck. Extreme stripped-core supernovae are so rare, just by probability astronomers will find tens of thousands more typical explosions before the next example turns up in their data.

However, that task is less daunting than it sounds.

In addition to the Zwicky Transient Facility where astronomers detected SN 2021yfj, Schulze and Modjaz both hailed the Vera C. Rubin Observatory, which is expected to detect a thousand supernovae each night of operation when it comes online in 2026. Though that telescope isn’t being built for spectroscopy, its ability to scan huge swaths of the sky at once will let astronomers identify explosions to analyze in more detail quickly, bringing us closer to an understanding of how massive stars live and die.

—Matthew R. Francis (@BowlerHatScience.org), Science Writer

Citation: Francis, M. R. (2025), This star stripped off its layers long before exploding, Eos, 106, https://doi.org/10.1029/2025EO250340. Published on 19 September 2025. Text © 2025. The authors. CC BY-NC-ND 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.

As a late-summer monsoon spread across California in recent weeks, it delivered hundreds of thousands of lightning strikes—record numbers in August and the first week of September. Those sparked hundreds of wildfires and, for many hikers, sheer terror.

Author(s): Mostafa Salahshoor

This study investigates electron kinetics in a direct current magnetron sputtering discharge, advocating for the use of the cumulative distribution function (CDF) as a superior alternative to conventional probability distribution functions (PDFs), such as the electron energy distribution function. A…

[Phys. Rev. E 112, 035209] Published Fri Sep 19, 2025

Local reports suggested that over 1,500 people died in this event, and a high death toll was reported by some international agencies. However, examination of satellite imagery casts significant doubt on this interpretation.

It has been widely reported that on 31 August 2025, a devastating landslide occurred at Tarasin (there are various spellings of this place) in the Marrah Mountains in Central Darfur, Sudan. Initial reports indicated that 1,000 people had been killed, making this the most deadly landslide of 2025 to date, whilst subsequent reports elevated this number to over 1,500. The reports were given credence by organisations such as Save the Children, who reported that 373 bodies had been recovered. There was only one reported survivor of the disaster.

However, it should also be noted that this very high total was not supported by government reports – noting of course that Sudan has extensive civil conflict, and that this area is not controlled by the government. BBC Verify examined the event too using Maxar satellite data, but could not identify a village that had been destroyed. The Washington Post reported that the United Nations subsequently reduced their estimated total loss of life to “scores”. On Bluesky, Dan Shugar pointed out that the reporting of 1,000 fatalities does not really stack up. The HydrologyNL Bluesky account has also posted some interesting analysis of this event.

The location of this landslide event is [13.01697, 24.38774]. This is a Planet image of the site draped onto the Google Earth DEM:-

Satellite image of the aftermath of the 31 August 2025 landslides in Sudan. Planet image draped onto the Google Earth DEM. Image copyright Planet, used with permission. Image dated 6 September 2025.

The marker highlights the rear scarp of the largest failure, although there are several landslides in the image. These landslides correlate with images from the site posted by news organisations (there are some images of unrelated landslides too, plus some AI slop). It appears that there have been multiple shallow landslides than have transitioned into channelised debris flows.

And this is a Google Earth view, with imagery from 2023 (with some cloud), showing the same area:-

The site of the 31 August 2025 landslides in Sudan. Google Earth image from 2023.

Some local reports of these landslides suggest that 1,500 houses were destroyed, based on information from the Sudan Liberation Movement. However, it is also notable that none of the published photography shows destruction on this scale. And the Google Earth images do not show any large settlements in the path of either the landslides themselves or the channelised debris flows. There is a cluster of houses at the foot of the main failure that has been destroyed:-

A cluster of buildings subsequently destroyed by the 31 August 2025 landslides in Sudan. Google Earth image from 2023.

However, this is a small number of buildings, not on the reported scale of losses. I have also looked at the Planet imagery from just before the landslide. There is no evidence of a large settlement in this area.

Thus, a reported death toll of 1,000-1,500 seems highly improbable, and the loss of 1,500 houses is not supported by the imagery or photography.

So, what are the possible explanations? We might consider the following:

1. The location is wrong – and the reports describe an event somewhere else. I consider this to be low probability, given the images that have been published;
2. Dan Shugar suggested that perhaps some sort of social event occurred in the path of the landslide – a wedding or suchlike. But the local reports are of 1,500 houses lost, and in general my experience is that this type of circumstance is reported, given the nature of the tragedy. Again, low probability.
3. The losses occurred a long distance down the channel. I cannot find such a site on the imagery, and I would expect that the location would be reported, and that photography would show the devastation. Again, this would seem to be low probaility.
4. There is mis-reporting, either accidentally or deliberately. I consider this to be high probability.

In remote areas, we have previously seen vastly inflated estimates of loss of life – a recent example was the 24 May Kaokalam landslide in Papua New Guinea. This can simply be a misunderstanding or the result of rumours. On the other hand, it can be deliberate. For example, loss of life can be inflated to attract additional resource for a population that is suffering extreme poverty, or it can be an attempt by the local forces to attract supplies for their own purposes. Others will be able to judge the most likely explanation.

I’m struggling to understand why reputable international agencies would appear to support these inflated reports, especially where they appear to provide testimony from the site.

Reference

Planet Team 2025. Planet Application Program Interface: In Space for Life on Earth. San Francisco, CA. https://www.planet.com/

Return to The Landslide Blog homepage Text © 2023. The authors. CC BY-NC-ND 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.

SummaryIn order to better understand the regional tectonics of western part of Africa (WA) and adjacent islands, joint inversion (Jinv) of body wave and surface wave measurements is conducted to construct new sets of crustal models. Teleseismic P-wave receiver function, receiver function horizontal-to-vertical ratio and Rayleigh wave ellipticity are jointly inverted based on a fast simulated-annealing scheme. All three types of observables are derived from single-station recordings and are primarily sensitive to structures beneath the station. The integration of these datasets through Jinv allows for complementary constraints, thereby improving the resolution of crustal velocity structures and the characterization of velocity variations with depth. We present improved and some new crustal structure parameters including bulk crustal VP/VS ratio, crustal thickness (H) estimates, and shear-wave velocity (VS) models beneath 25 broad-band seismic stations across inland, coastal, and island terrains. Using an improved approach involving the correction of misorientation error effect from seismic waveform data, the data quality is well-enhanced leading to improved resolutions of structures across the different terrains. Results from H-k and crustal models showed a general northward thinning from Congo Craton (> ∼48 km) towards the Lower Benue Trough (∼15 km), and from coastal terrain along Gulf of Guinea (< ∼44 km) towards Mauritanian Belt (> ∼16 km). Compared to other terrains, the islands show very thin depth to the Moho, but higher than the global estimates. In the Mauritanian-Senegal Basin, sharp differential in crustal thickness and Jinv results at neigbouring G.SOK and G.MBO are observed, where slower Vs revealed a LVZ anomaly at G.SOK in contrast with faster Vs at G.MBO—which could be due to local subsidence from sediment loading, or uplift from tectonic activities. In the upper-middle crust, the Jinv imaged structures with faster VS characteristic of felsic to intermediate bulk crustal composition beneath inland terrain (West Africa Craton, Congo Craton, Hoggar), attributed to highly depleted and stable nature of the cratonic lithosphere, contributing to faster VS compared to other terrains. Low velocity structures underlying the island stations are attributed to partial melts and high temperature materials, indicative of volcanic and Basaltic composition. Similarly, the low velocity structures deciphered beneath coastal stations G.SOK and AF.EDA could be related to the structures in their adjacent areas of Tenerife and the Cameroon Volcanic Line, respectively. The nbroad range of VP/VS (∼1.58–1.85) ratio along the coastal terrains demonstrates its complexity; from the low VP/VS which may be attributed to indurated or low porosity sedimentary materials, and high VP/VS —typical of cracks, fluids inundated sedimentary or volcanic materials. Island terrain are associated with higher bulk VP/VS indicative of volcanics and Mafic-Basaltic materials, with the low velocity zones (LVZs) suggestive of the presence of magmatic materials. These broad crustal configuration highlights the complexity and provides new insight for developing more accurate regional model for western Africa and its adjacent islands, and global reference models in future studies.

Between a third and half of all soil carbon on Earth is stored in peatlands, says Tom and Marie Patton Distinguished Professor Joel Kostka. These wetlands—formed from layers and layers of decaying plant matter—span from the Arctic to the tropics, supporting biodiversity and regulating global climate.

If it feels like headlines reporting 100 or 1,000-year floods and megafires seem more frequent these days, it's not your imagination.

As I walked out onto the frozen Arctic water off Utqiagvik, Alaska, for the first time, I was mesmerized by the icescape.

The water cycle has become increasingly erratic and extreme, swinging between deluge and drought, according to a new report from the World Meteorological Organization (WMO). It highlights the cascading impacts of too much or too little water on economies and society.

Streamflow drought—when substantially less water than usual moves through rivers—can seriously disrupt the welfare of nearby communities, agriculture, and economies. Synchronous drought, in which multiple river basins experience drought simultaneously, can be even more severe and far-reaching.

In 2018, the Hayabusa2 mission successfully encountered asteroid Ryugu. The Japan Aerospace Exploration Agency (JAXA) spacecraft arrived at, touched down on, collected samples of, and lifted off from the asteroid. It returned samples to Earth in 2020.

With plenty of fuel left for its extended mission, called Hayabusa2# or “Hayabusa2 Sharp,” the spacecraft raced off to its next objective, a high-speed flyby of asteroid 98943 Torifune in 2026. If all goes well with that rendezvous, the craft will attempt its final objective: an encounter with and touchdown on asteroid 1998 KY26 in 2031.

But that final objective may prove more difficult than initially imagined. New ground-based observations of 1998 KY26 have revealed that the asteroid is 3 times smaller than previously thought and spins twice as fast.

“We found that the reality of the object is completely different from what it was previously described as,” Toni Santana-Ros, lead author of a new study on 1998 KY26 and an asteroid researcher at Universidad de Alicante and Universitat de Barcelona in Spain, said in a statement.

Small and Fast

Astronomers discovered 1998 KY26 in 1998 when it came within 2 times the Earth-Moon distance. Radar and visual observations shortly after discovery estimated that the asteroid was about 30 meters across and rotated once every 10.7 minutes, the fastest-rotating asteroid known at that time. As the asteroid moved away, it became too faint to see for more than 2 decades. When Hayabusa2’s mission scientists selected targets for its extended mission, they relied on those 1998 calculations.

The asteroid completes one spin every 5 minutes and 21 seconds, less time than it takes to listen to Queen’s “Bohemian Rhapsody.”

Finally, in 2024, 1998 KY26 came close enough to Earth—12 times the distance to the Moon—to observe again. Using four of the most powerful ground-based telescopes available, Santana-Ros and his colleagues watched the diminutive asteroid tumble and spin from multiple angles, allowing them to calculate a more accurate spin rate than was possible with the limited radar and photometry in 1998.

They calculated that the asteroid completes one spin every 5 minutes and 21 seconds, less time than it takes to listen to Queen’s “Bohemian Rhapsody.” The team then combined those new observations with the 1998 radar data to recalculate the asteroid’s size. They found that instead of being roughly 30 meters in diameter, 1998 KY26 is just 11 meters, or about the length of a telephone pole. The team published these results in Nature Communications on 18 September.

Asteroid Ryugu (left) is roughly 82 times the size of asteroid 1998 KY26 (right). Credit: ESO/M. Kornmesser; Asteroid models: T. Santana-Ros, JAXA/University of Aizu/Kobe University, CC BY 4.0

“The smaller the asteroids get, the more abundant they are—but that also means that they are harder to find,” explained Teddy Kareta, a planetary scientist at Villanova University in Pennsylvania who was not involved with the new discovery. “The fact that this new paper finds such a small size for KY26 is tremendously interesting on its own—Hayabusa2 will be able to explore an extremely understudied population—but it also means that we might not have a tremendous number of known objects to compare to as well.”

A Challenge and an Opportunity

The new size and spin measurements of 1998 KY26 will make Hayabusa2’s planned touchdown more challenging, the researchers wrote. However, this is not the first time that an asteroid rendezvous mission has had to adjust its expectations mid-flight. Both Ryugu and Bennu, the first target of NASA’s Origins, Spectral Interpretation, Resource Identification, Security–Regolith Explorer (OSIRIS-REx) mission, had rougher surfaces than expected, requiring the respective missions to adjust their sample collection methods. Too, the OSIRIS-REx team learned that Bennu was actively spitting out material only when the spacecraft got close, which led them to change their plan for orbital insertion.

Despite the new challenges with 1998 KY26, Hayabusa2#’s team has a big advantage: 6 years to rework their game plan.

“The Hayabusa2 team are incredibly smart, hardworking, and have a ton of experience under their belts, but I’m sure that this kind of result is causing a bit of hand-wringing and concern for them even if the spacecraft is fully capable,” Kareta said.

“We have never seen a ten-metre-size asteroid in situ, so we don’t really know what to expect and how it will look.”

“I’m sure even the team has their doubts about whether or not the original plan was possible, but if I had to bet money, I still think the team will try [to touch down],” they added. “You set yourself up for success by building a great spacecraft and collecting a great team of engineers and scientists to staff it, but it’s still a bet every time you try something new.”

Even if a touchdown on 1998 KY26 ultimately proves impossible and Hayabusa2# simply flies on by, asteroid scientists will still gain valuable information about an incredibly common but hard-to-spot type of small asteroid.

“We have never seen a ten-metre-size asteroid in situ, so we don’t really know what to expect and how it will look,” Santana-Ros wrote.

“In many ways, a spacecraft visit to it now is even more exciting than it was before,” Kareta said.

—Kimberly M. S. Cartier (@astrokimcartier.bsky.social), Staff Writer

Citation: Cartier, K. M. S. (2025), Hayabusa2’s final target is 3 times smaller than we thought, Eos, 106, https://doi.org/10.1029/2025EO250353. Published on 18 September 2025. Text © 2025. AGU. CC BY-NC-ND 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.

In May, a landslide above Blatten in the canton of Valais buried most of the village under a mass of ice, mud and rock, an event that has prompted in-depth research. At a recent conference in Innsbruck, UZH researcher Christian Huggel presented his findings on the link between the landslide and climate change.

Source: AGU Advances

Streamflow drought—when substantially less water than usual moves through rivers—can seriously disrupt the welfare of nearby communities, agriculture, and economies. Synchronous drought, in which multiple river basins experience drought simultaneously, can be even more severe and far-reaching.

Recent observations and modeling suggest that on the Indian subcontinent, where major rivers support more than 2 billion people, the likelihood of synchronous drought is increasing as summer monsoons weaken, the Indian Ocean warms, and anthropogenic emissions and excessive groundwater pumping continue. However, little is known about the long-term patterns of synchronous drought in India, in part because streamflow data don’t offer information about the distant past.

By combining several decades of streamflow measurements from 45 gauge stations along India’s major rivers with high-resolution temperature and precipitation data and data from a range of paleoclimate proxies, Chuphal and Mishra have now reconstructed streamflow records across more than 800 years.

To look farther back in time, the researchers turned to the Monsoon Asia Drought Atlas, which comprises tree ring data indicating summer drought conditions across Asia between 1200 and 2012. They also considered historical records of climate patterns like El Niño, the Pacific Decadal Oscillation, and the Indian Ocean Dipole to explore connections among drought frequency, reoccurrence, and synchronicity. And they used two models from the Paleoclimate Modeling Intercomparison Project Phase 4 (PMIP4) that are part of the Coupled Model Intercomparison Project Phase 6 (CMIP6) to simulate precipitation and temperature data, as well as a hydrological model to simulate streamflow from 1200 to 2012.

With all this information, the researchers created their own reconstruction model that captured historical droughts driven by monsoon failures and connected low river levels to periods of drought-induced famine. Their findings revealed an increased frequency in synchronous drought between 1850 and 2014 compared with preindustrial centuries—an increase they surmise was likely caused by the warming climate. The researchers also suggest that future synchronous droughts may threaten water security throughout India. (AGU Advances, https://doi.org/10.1029/2025AV001850, 2025)

—Rebecca Owen (@beccapox.bsky.social), Science Writer

Citation: Owen, R. (2025), Droughts sync up as the climate changes, Eos, 106, https://doi.org/10.1029/2025EO250324. Published on 18 September 2025. Text © 2025. AGU. CC BY-NC-ND 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.

In recent years, the North American beaver (Castor canadensis) has been increasingly recognized as a valuable on-site engineer to help communities meet water management goals. Beavers are famously “eager” to build dams, which slow the flow of streams and allow wetland areas to grow.

Until now, however, land managers didn’t have a way to estimate how much water beaver reintroduction could actually bring to a habitat. Not every beaver dam results in a sprawling ponded complex; sometimes they result in smaller areas with less water retention than meets the needs of the community.

In a study published last month in Communications Earth and Environment, researchers from Stanford University and the University of Minnesota were able to link the amount of surface water in beaver ponds across the western United States to the features in those landscapes that make beaver ponds bigger.

Big, Beautiful…Beaver Ponds

Oftentimes, beavers will chain together multiple dams and ponds to form beaver pond complexes. The complexes increase an area’s water retention, cool water temperatures, and provide natural firebreaks. These wetland habitats also give the semiaquatic rodents ample room to roam and allow other species (such as amphibians, fish, and aquatic insects) to flourish.

Beaver pond complexes like the one in Happy Jack Recreation Area create habitat for wetland creatures big and small, like this (very large) moose. Credit: Emily Fairfax

“Our models highlight the landscape settings where ponds grow largest, helping target nature-based solutions under climate stress.”

The advantages of beaver pond complexes aren’t going unnoticed—the reintroduction of beavers to the North American landscape is an increasingly popular strategy for land managers looking to naturally improve a waterway.

“Managers need to know where beaver activity—or beaver-like restoration—will store the most water and maximize the environmental benefits, such as providing cooling and enhancing habitat quality” said Luwen Wan, a postdoctoral scholar at Stanford and the new study’s lead author. “Our models highlight the landscape settings where ponds grow largest, helping target nature-based solutions under climate stress.”

While improving water retention is a goal of many watershed management projects, especially in the increasingly drought-prone western United States, the researchers also emphasized that creating the largest possible ponds might not be the right solution for every area.

“It’s worth thinking about what we are actually asking of these beavers, and is that reasonable?”

“Bigger ponds are not always better,” said Emily Fairfax, coauthor on the study and assistant professor at the University of Minnesota. Fairfax explained that larger ponds are great for when the goal of the project involves water retention, but smaller ponds could be a better fit for a project in which the goals are pollution removal or increasing biodiversity. “It’s worth thinking about what we are actually asking of these beavers, and is that reasonable?”

How to Design a Dream Stream

Speaking on the main findings of the study, Wan said that she and her colleagues “found a clear link between the total length of beaver dams and the size of the ponds they create.” Additionally, they observed that the biggest ponds were found “where dams are longer, stream power is lower to moderate, and woody vegetation is of moderate [6–23 feet, or 2–7 meters] height.”

Included in the study were 87 beaver pond complexes across the western United States, encompassing almost 2,000 dams. Using high-resolution aerial imagery from the National Agriculture Imagery Program (NAIP), the team was able to connect the observed ponded area to different landscape measurements like soil characteristics, stream slope, vegetation metrics, and more.

The researchers chose NAIP imagery for its high spatial resolution and ability to cover large areas (visiting every beaver pond in the field would take too much time). Wan noted that while NAIP aerial imagery was the right fit for this project, it isn’t perfectly beaver proof. The imagery is updated every 2–3 years during the growing season, which may introduce some errors, like missing ponds even when dams have already been constructed.

Using remote sensing to predict where beaver reintroduction would be a successful match to the needs of a watershed isn’t a new idea. One frequently used model mentioned in the study is the Beaver Restoration Assessment Tool (BRAT). BRAT allows researchers to identify how many dams a given stream would likely be able to host. “That’s really important information to have,” said Fairfax, “but that doesn’t tell us how big the dams are, or how much water they could be storing.”

When Beavers Aren’t Best

Findings from this study are also helpful when selecting sites for beaver dam analogs (BDAs). These human-made structures are alternatives to beaver reintroduction that mimic beaver dams to achieve the same ecosystem benefits the beavers would bring. They are often the right tool when a waterway is too degraded to host a beaver population.

BDAs raise water levels and allow the preferred foods of beavers (such as willows and alders) to take root, giving “a little push” to the process of reestablishing a beaver population, explained fluvial geomorphologist and associate professor Lina Polvi Sjöberg from Umeå University in Sweden. Polvi was not involved in the new study.

Fairfax added that BDAs are a useful tool but are not equivalent to actual beaver dams. With beaver dams, a living animal is always present, so the land managers can count on the “maintenance staff on-site” to constantly update and monitor the waterway.

The Beavers Are Back in Town

North American beaver populations are still on the rebound from a long history of trapping and habitat loss that came with European colonization of the continent. “We are at maybe 10% of the historic population, and we actually don’t know if it’s still growing,” Fairfax said. Modern threats to beaver populations include highways and man-made dams, she added, which prevent beavers from freely moving back to places they once were.

Not everyone is quick to welcome North America’s largest rodent back to their neighborhood with open arms. Though public perceptions of beavers are shifting from pest to watershed management partner, the potential for contention still remains. Beavers occasionally build their dams in less-than-ideal locations, a situation that can result in flooded private properties and damaged infrastructure. The study notes that human influence (like trapping and land use conflicts) is a factor that land managers must consider but is not captured in statistical models.

Beavers Worldwide

The researchers found what makes beaver dams bigger in the western United States, but scientists say it will be important to replicate this study in different regions of North America, especially as beaver habitat expands northward as a result of climate warming.

“North American beavers are all one species, Castor canadensis. A beaver in Arizona is the same species as a beaver in Alaska. They all have the same instincts,” said Fairfax, “but beavers also do learn and adapt to their environments pretty strongly.”

She added that beavers will use the materials available to them, such as a colony in Yukon, Canada, that has been observed using rocks as dam-building material. “Whenever we build a model that describes what beavers are doing, there is a chance that it’s going to have a strong geospatial component to it,” Fairfax said.

Polvi agreed, stating that she hadn’t seen many studies using remote sensing methods to estimate the suitability of a stream for beaver reintroduction outside of the western United States. Putting things into a wider perspective, she added that some defining features of the American West, like the semiarid climate and large expanses of undeveloped public land, aren’t applicable to other regions of the world.

In an email, Wan said the next steps from this study include further exploring beavers’ ponded complexes across larger areas and “quantifying the ecosystem services these ponds provide, such as enhancing drought resilience.”

—Mack Baysinger (@mack-baysinger.bsky.social), Science Writer

Citation: Baysinger, M. (2025), What makes beaver ponds bigger?, Eos, 106, https://doi.org/10.1029/2025EO250341. Published on 18 September 2025. Text © 2025. The authors. CC BY-NC-ND 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.

Source: Global Biogeochemical Cycles

This is an authorized translation of an Eos article. 本文是Eos文章的授权翻译。

多年来，海洋学家们一直困惑于为何算法会在南极偏远海域的卫星图像中检测到神秘的高浓度颗粒无机碳 (PIC)。在其他地区，高PIC是单细胞浮游植物大量繁殖的标志，这种浮游植物被称为颗石藻(coccolithophores)，这些植物闪亮的碳酸钙外壳会将光线反射回卫星。然而，长期以来人们一直认为这些极地水域温度过低，不适合颗石藻生长。

如今，得益于 Balch 等人的最新船载测量数据，这个谜团终于解开了。他们发现了一种名为硅藻(diatoms)的不同类型的浮游植物，当硅藻的反射性硅质外壳（或称硅藻壳，frustules）浓度极高时，其反射率可以模拟 PIC 的反射率。这种反射率可能导致卫星算法将这些遥远的南部海域错误地归类为高 PIC 区域。

同一研究团队此前的船上观测已证实，来自颗石藻的PIC是大方解石带的成因——大方解石带是一个巨大的、季节性的、反射性的水环，环绕南极洲北部较温暖的水域。然而，在更南端，南极大陆周围异常明亮的区域仍然无法解释，推测的成因包括松散的冰块、气泡或反射性的冰川“粉”（被侵蚀的岩石颗粒）被释放到海洋中。

研究人员乘坐R/V Roger Revelle号从夏威夷向南航行，进入较少被探索的水域，这里以冰山和波涛汹涌的大海而闻名。他们测量了PIC和二氧化硅的含量，确定了光合作用速率，进行了光学测量，并在显微镜下观察了微生物。这些数据表明，这些偏远地区的高反射率主要是由硅藻壳引起的。

然而，研究人员也惊讶地发现极地水域中有一些颗石藻，这表明这些浮游植物可以在比以前想象的更冷的海水中生存。

由于颗石藻和硅藻在海洋碳固定中都发挥着重要作用，因此这些发现可能对地球的碳循环具有重要意义。研究人员表示，这项研究还可以为改进卫星算法提供参考，以便更好地区分PIC和硅藻壳。(Global Biogeochemical Cycles, https://doi.org/10.1029/2024GB008457, 2025)

—科学撰稿人Sarah Stanley

This translation was made by Wiley. 本文翻译由Wiley提供。

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Text © 2025. AGU. CC BY-NC-ND 3.0
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Editors’ Vox is a blog from AGU’s Publications Department.

Today, in Eos, American Geophysical Union (AGU) Publications recognizes a number of outstanding reviewers for their work in 2024, as selected by the editors of each journal.

Peer review is a crucial component of the scientific process and is vital for promoting clarity and accuracy in how science is communicated.

Peer review is a crucial component of the scientific process and is vital for promoting clarity and accuracy in how science is communicated. In an era with so many ways to share ideas and research, a healthy and thriving system of peer review ensures that we encourage clear communication and maintain the highest integrity in our scientific publications. At AGU, the peer review process is conducted by scientists, starting with the journal editors. It is then the peer reviewers who take time away from their own research to volunteer time and expertise to help other scientists improve their articles and to aid publication decisions. The work of these colleagues ensures that thousands of articles each year receive independent feedback as part of a robust process of consideration and evaluation for publication. We are thankful for their efforts to make our science stronger.

Discoveries and solutions in the Earth and space sciences rely on increasingly complex approaches and datasets reflected in the papers that share their results. Peer reviewers bring their substantial expertise to evaluate detailed and intricate science conducted by teams of researchers large and small. Reviewers must assess insights gleaned from studies utilizing more and new techniques, data, and simulations that increase in scale and scope each year. As a result, both the value and challenge of peer reviewing keeps growing. Science benefits when our community rises up to support the opportunities afforded by the work reported in AGU journals by providing thoughtful and insightful feedback through peer review.

The outstanding reviewers listed here have provided in-depth, valuable, and timely feedback and evaluations, often through multiple revisions, and multiple manuscripts, that have led to clearer and greatly improved final published papers. Their contributions helped raise the quality of submissions received from around the world, delivering valuable feedback that makes for better scientific discourse.

Many Reviewers: A Key Part of AGU Journals

While we recognize these few outstanding reviewers, we also must acknowledge the incredible service to the community by all the researchers who have conducted reviews to help ensure the quality, timeliness, and reputation of AGU journals. We also welcome new and first-time reviewers who have joined the family of community servants who act as integrity stewards and have been providing authors with valuable feedback to improve their science and communication. In 2024, AGU received over 20,000 submissions, which was a significant increase from 2023, and published 7,517 papers. Most submissions were reviewed multiple times—in all, 17,947 reviewers completed 44,656 reviews in 2024.

The past several years continued to be a rollercoaster for researchers, editors, and peer reviewers. The challenges of maintaining the peer review system remain at an all-time high. Volunteer reviewers in Europe and the United States receive more invitations than they can accept, while research output in China is now the highest of any country. AGU journals continue to make progress in balancing the efforts of colleagues serving our community via conducting peer reviews even as they often struggle to invite a proportional number of reviewers across the globe. Likewise, early career researchers observe some of their more senior colleagues being overburdened by invitations and wonder why they receive so few invitations themselves. AGU is committed to building further entrance points to peer reviewing including its co-reviewing program and peer reviewing programs in individual journals.

Reviewers play a central role in the rapid feedback and publishing of new science that is at the heart of advancing the Earth and space sciences.

Amidst these challenges, each AGU journal worked to maintain low time frames from submission to first decision and publication, and consistently maintained industry-leading standards. Reviewers play a central role in the rapid feedback and publishing of new science that is at the heart of advancing the Earth and space sciences.

Editorials in each journal express our appreciation along with reviewer recognition lists. Our thanks are a small acknowledgment of the large service that reviewers bear in improving our science and its role in society.

Additional Thanks

In addition, we are working to highlight the valuable role of reviewers through events at AGU’s Annual Meeting and other meetings.

We will continue to work with the Open Researcher and Contributor ID (ORCID) network to provide official recognition of reviewers’ efforts, so that reviewers receive formal credit there. As of 10 July 2025, we have over 116,000 ORCIDs up from 100,000 ORCIDs one year ago.

Getting Your Feedback

We value your feedback, including ideas about how we can recognize your efforts even more, improve your experience, and increase your input on the science. Feel free to send your comments to publications@agu.org. We look forward to hearing from you!

Once again: Thanks to our Outstanding Reviewers of 2024!

—Matt Giampoala (mgiampoala@agu.org, 0000-0002-0208-2738), Vice President, Publications, American Geophysical Union; and Steven A. Hauck II (0000-0001-8245-146X), Chair, AGU Publications Committee

Citation: Giampoala, M., and S. A. Hauck II (2025), In appreciation of AGU’s outstanding reviewers of 2024, Eos, 106, https://doi.org/10.1029/2025EO255029. Published on 18 September 2025. This article does not represent the opinion of AGU, Eos, or any of its affiliates. It is solely the opinion of the author(s). Text © 2025. The authors. CC BY-NC-ND 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.