A new phase of solid superionic ice has been created for the first time in the laboratory. By heating a tiny sample of ultrapure water while compressing it to extreme pressures, physicists at the French Alternative Energies and Atomic Energy Commission (CEA) succeeded in forming an ice phase that features a hexagonal close-packed (hcp) structure and liquid-like hydrogen diffusing through a solid lattice of oxygen atoms. This demonstration could help us better understand the structure of ice giant planets such as Uranus and Neptune, which may harbour this form of ice deep within their interiors.

Unlike water’s familiar liquid, vapour and ice phases, superionic ice can only exist when water is subjected to tens or even hundreds of GPa of pressure at temperatures above 1000-2000 K. Under these conditions, theory predicts that hydrogen ions (protons) diffuse so readily through empty sites in water’s oxygen lattice that the material’s ionic conductivity may exceed 100 Siemens per centimetre, making it almost as conductive as metals. The melting temperature of this form of ice is also extremely high, reaching several thousand kelvin as new ice structures develop that feature a close-packed oxygen lattice.

Diamond anvil cells and X-ray diffraction spectra

To create super-high pressures in the laboratory, researchers typically use diamond anvil cells, which are tiny cavities in which samples are tightly compressed between the tips of two opposing diamond surfaces. In the new work, a CEA team led by physicists Alexis Forestier and Gunnar Weck added two high-thermal-conductivity cup-shaped discs made of boron-doped diamond to the diamond anvil surfaces. This set-up enabled them to apply pressure while heating their 12 micron-sized sample uniformly with lasers, thereby avoiding the large temperature gradients that complicate measurements in conventional diamond anvil cells.

Forestier, Weck and colleagues heated their sample of ultrapure water from 300 to 2630 K while applying pressures between 80 and 229 GPa. Thanks to the Extremely Brilliant Source’s sub-micron beam – part of the ID27 beamline at the European Synchrotron Research Facility in Grenoble – they were able to obtain high-quality X-ray diffraction spectra despite the small size of their sample. According to the CEA researchers, these spectra clearly showed a new hexagonal close-packed (hcp) phase of superionic ice emerging alongside a previously observed face-centred cubic (fcc) phase across a pressure range of 130-200 GPa and temperatures above 1800 K.

A link to Uranus and Neptune

The discovery brings the total number of superionic phases of water to three, with the other being the body-centred cubic phase first observed in 2016. But that’s not all. Forestier, Weck and colleagues say that their results, which they report in Physical Review Letters, could also help explain the magnetic fields of Uranus and Neptune.

Unlike the Earth’s magnetic field, these fields are skewed and off-centre with respect to the planets’ axis of rotation. These properties have led scientists to hypothesize that instead of being generated by the motion of molten iron in the planet’s core (as on Earth), the magnetic fields of Uranus and Neptune could arise from conductive superionic warm dense ice (composed of water, ammonia and methane) in the planets’ outer third.

“The experimental observation of this new hcp superionic phase now provides a rationale for incorporating its mechanical properties and ionic conductivity into these models of planetary interiors,” Forestier says. “Indeed, this phase can coexist with the fcc superionic phase and become more stable at higher pressures (above 150–200 GPa), and so probably exist deeper within the inner shell of these ice giants.”

The researchers’ next step will be to precisely define regions of the phase diagram where pressure and temperature are stable; map out the transition lines between the different phases (molecular and superionic); and understand how the new hcp phase behaves as it melts. This will help confirm whether these phases are stable and present within Uranus and Neptune, Forestier tells Physics World.

“We also want to obtain more direct experimental signatures of superionic behaviour, beyond the thermal expansion we observed,” Weck adds. “Brillouin spectroscopy measurements, for example, could reveal anomalies in the speed of sound, strengthening the evidence for proton diffusion.”

The post New type of superionic water ice observed for the first time appeared first on Physics World.

The Moon’s polar regions may be less hostile to microbes than previously thought. This is the new finding from researchers at NASA and the University of Maryland in the US who say that future crewed missions to the lunar south pole will have to be carefully thought out to limit the unintended transfer of Earth life forms.

High ultraviolet radiation and temperatures make the Moon’s surface a harsh place and not somewhere bacteria and other micro-organisms can easily survive. This is particularly true for the equatorial regions, where all previous crewed missions have been sent. Things might be quite different at the lunar poles, however, since sunlight strikes these high-latitude regions at a low angle because of the Moon’s minimal tilt to the Sun of 1.5°. The result is long permanent shadows where it is cooler. The moonscape is also as rugged here as elsewhere with mountains and hills, which also cast shadows, and deep craters protected from the Sun’s heat and ultraviolet flux. These conditions allow for water ice too.

Because of these unique properties, future crewed missions, such as NASA’s Artemis IV, are scheduled to go to the Moon’s south pole, which has also been identified as a possible future location for a human outpost. The polar regions have already been observed by spacecraft such as ESA’s SMART-1, India’s Chandrayaan, Japan’s Kaguya and NASA’s Lunar Reconnaissance Orbiter. These provided a wealth of information that will be used to prepare future missions.

The problem is that no matter how stringent the sterilization procedures are prior to take-off, the astronauts on these missions will take microbes from Earth with them. Indeed, humans carry millions of microbes on their skin and even more in their bodies.

Landing sites for Artemis IV

To investigate whether microbes could survive in the polar regions, the researchers, led by Prabal Saxena, who works at NASA’s Goddard Space Flight Center, and Stefano Bertone at the University of Maryland, modelled how bacteria and fungi commonly found on human skin would behave in the environment of three candidate landing sites for the upcoming Artemis IV mission. The researchers began by making highly resolved spatial maps of the topography in these regions that included ruggedness, slopes and shadowing effects. They also modelled the UV exposure and temperature in these regions to identify specific locations where micro-organisms could survive for at least 24 h.

They obtained seasonal temperature data on length scales of 240 m from measurements by Lunar Reconnaissance Orbiter’s (LRO) Diviner. As for estimated regional UV (≤320 nm) fluxes, these were gleaned from averaged illumination maps with a pixel scale of 60 m based on topography derived from LRO Lunar Orbiter Laser Altimeter (LOLA) measurements.

“Since the temperatures at the lunar poles are rarely high enough to kill bacteria and low temperatures can preserve microbes on Earth, UV radiation is generally likely to be more dangerous in these regions, says Saxena. “We therefore analysed UV fluxes at finer spatial scales using a technique called ray tracing, and for some regions, included optical effects such as reflection and refraction as sunlight hits the Moon’s surface, leveraging updated LOLA-based topography maps on a scale of 5 m/pixel.”

Understanding how sunlight behaves at the poles is crucial, he adds. “Since the Moon has a very small axial tilt, the Sun appears to hover just above the horizon here, so even small hills and rocks can prevent light from reaching lower-lying ground, creating small, shadowed areas protected from UV rays.”

Up to seven days survival

The simulations revealed that the bacteria and fungi studied could survive in certain niches for up to or potentially beyond seven days. One particular fungus, the Aspergillus, is particularly resistant to UV radiation and could potentially survive in 15 to 30% of the areas assessed, even those that receive some sunlight during the lunar winter. The reconstructions also showed that all five microbes in this study, Bacillus, Deinococcus, Staphylococcus, Aspergillus and Fusarium could possibly survive in certain areas of the De Gerlache Rim’s permanently shaded regions, including when scattered UV light is incorporated into the simulations.

Survival does not mean growth (which requires active metabolism and potential reproduction), however, stresses Saxena. Indeed, surviving microbes are in a dormant, so-called cryptobiotic state and would only grow if the conditions were amenable to life – which is not the case for the Moon as we currently understand it.

“Cells may also be dead,” he tells Physics World, “but even dead cells may persist in the environment as another potential source of contamination.”

The work could apply beyond the Moon, he says. Indeed, a number of different airless bodies such as Mercury, Ceres, some asteroids and comets and exoplanets that may have similar properties could also have potential survivable niches for microbial life. Understanding how these niches may exist, how life may be transferred to them and how human exploration may leave its mark will all serve as a key testbed for future potential human exploration of Mars, which likely has far more habitable environments.

“We need to understand what was there before us, because when we search for signs of life beyond our planet on these bodies, we will want to make sure it’s not stuff we brought,” says Saxena.

The research is described in Science Advances.

The post Microbes may survive at the Moon’s south pole appeared first on Physics World.

Although the famous Carrington Event of 1859 is often described as the first major space weather event to affect technology, earlier incidents did occur. Historical records show that telegraph systems were disrupted by geomagnetic storms as early as the late 1840s.

The post Study: Famous ‘Space Weather’ Train Delay Actually Happened Seven Years Later appeared first on Sci.News: Breaking Science News.

It started as a routine data-quality check. But as Robert Wagner, a scientist with NASA’s Lunar Reconnaissance Orbiter (LRO), scanned a giant Moon map on his computer screen, an unusually large bright spot circled by a dark halo caught his eye, as it implied that surface material in that area had been shaken up.

“I just stopped, dropped everything, and started looking into what that spot was,” said Wagner, an image-processing specialist from Intuitive Machines who works with data from the Lunar Reconnaissance Orbiter Camera (LROC) system.

By comparing before and after images of the Moon, Wagner realized he had discovered the largest, newly formed crater ever found in the solar system, as scientists reported Wednesday in Science Advances. This discovery highlights the value of NASA’s Moon orbiter data in studying a dynamic landscape as the agency advances a sustained human presence and expanded scientific and commercial activity on the Moon.

Officially named McGetchin after pioneering lunar scientist Tom McGetchin, the crater formed on the Moon’s eastern edge sometime between April 11 and May 22, 2024, after a comet or asteroid the size of a three- to six-story building hit the surface.
 
The crash left a crater, 728 feet wide, that spans the length of two football fields. And at 141 feet deep, the crater could fit three vertically stacked yellow school buses.
 
Scientists estimate that an impact of this magnitude happens on the Moon about once in a century or even longer.

Moon takes some hits

For more than 17 years, LRO has been circling the Moon and using its seven instruments to map the topography, surface composition, temperature, and radiation environment there. The spacecraft’s team has identified at least 1,000 new impact craters throughout the mission and flagged 100,000 more surface changes from an object smashing into the Moon or from the debris that flung out after.

With no atmosphere to slow them or burn them up, space rocks and other objects easily reach the lunar surface. Most are much smaller compared to the object that carved out McGetchin crater. The smallest craters scientists can distinguish from LRO images are about 30 feet wide, the length of a three-story building laid on its side, made by rocks about 43 inches wide, the size of a monster-truck tire. Scientists estimate that impacts of this scale produce about 140 new craters across the Moon each year. But most new ones are made by microscopic projectiles that leave holes too small to identify in orbital images.

With its numerous instruments, the spacecraft can observe changes to the lunar surface that aren’t apparent in the LROC images alone. After the crater was discovered, scientists working with LRO’s thermal instrument, Diviner, made follow-up observations of the site. They found a 4-mile-wide area around the crater that is about 16 degrees Fahrenheit cooler at night than its surroundings.

Reporting in a second paper Wednesday in the same journal, researchers say that the cooling happens because the impact fluffs up the regolith around the crater, making it less dense and therefore less able to retain heat.

The large extent of this “cold spot” is striking, scientists say, because it shows that impacts can modify the Moon’s surface far beyond the crater itself. These physical changes could affect how rover wheels interact with the surface, for instance.

Road to discovery

The LROC system collects images from about 60 miles above the Moon as LRO loops from pole to pole. The system includes two cameras that capture high‑resolution black‑and‑white images and one camera for moderate‑resolution multispectral images. Over the years and thousands of passes, scientists have built maps detailed enough to spot not only new craters, but also landslides, landers, seismic faults, and even hints of lava tubes.

LROC scientists regularly analyze close-up images of small portions of the Moon’s surface taken by the Narrow-Angle Camera. Using these images, they look for changes that are typically less than 30 feet across. But every few years the team searches for large (wider than 150 feet) features by creating global Moon maps and comparing them to older versions.

That’s what Wagner was doing on Oct. 24, 2025, when he came across McGetchin. Using images from LROC’s Wide-Angle Camera, which captures broad views with pixels the size of football fields, he stacked hundreds of “before” and “after” frames with software designed to highlight change. Anything that stayed the same turned gray while anything different showed up as bright or dark patches.

While the process sounds straightforward, spotting real craters requires a lot of manual work. The software flags every tiny shift in lighting or shadow, generating hundreds of false alarms. For this reason, Wagner typically verifies the software, looking for small fuzzy halos around pixel‑wide bright points, which indicate splashes of regolith around a new crater.

Spanning hundreds of pixels, McGetchin stood out immediately. “It was by far the most obvious impact debris pattern I’ve ever seen in one of these images,” Wagner said.

After his discovery, scientists turned to the Narrow-Angle Camera, which takes much sharper views at about 3 feet per pixel. This camera’s close-up images, taken as LRO flew over the impact site again, revealed the crater size, shape, and how the surrounding terrain was affected. These images also helped researchers estimate the size and force of the rock fragment that formed the new crater, details that are expected to appear in a future paper.

Banner image caption: A zoomed-in view of the Moon, with debris around McGetchin crater visible as a white spot circled by a dark halo just right of center of the image (marked with black arrows). This is the view that Robert Wagner saw on Oct. 24, 2025, during a routine data-quality check. Wagner is an image processing specialist for NASA’s Lunar Reconnaissance Orbiter Camera, a system of three cameras. Using images from the Wide-Angle Camera (WAC), which captures broad views with pixels the size of American football fields, he stacked hundreds of images captured by WAC over the last several years with software designed to highlight change. Anything that stayed the same is gray; anything that changed showed up as bright or dark patches. The stripes in the image are due to slight changes in lighting between the older and newer images. This image composite shows an area of the Moon approximately 900 miles across.

The post NASA’s Moon Orbiter Spots New, ‘Once-in-Century’ Moon Crater appeared first on NASA Science.

It started as a routine data-quality check. But as Robert Wagner, a scientist with NASA’s Lunar Reconnaissance Orbiter (LRO), scanned a giant Moon map on his computer screen, an unusually large bright spot circled by a dark halo caught his eye, as it implied that surface material in that area had been shaken up.

“I just stopped, dropped everything, and started looking into what that spot was,” said Wagner, an image-processing specialist from Intuitive Machines who works with data from the Lunar Reconnaissance Orbiter Camera (LROC) system.

By comparing before and after images of the Moon, Wagner realized he had discovered the largest, newly formed crater ever found in the solar system, as scientists reported Wednesday in Science Advances. This discovery highlights the value of NASA’s Moon orbiter data in studying a dynamic landscape as the agency advances a sustained human presence and expanded scientific and commercial activity on the Moon.

Officially named McGetchin after pioneering lunar scientist Tom McGetchin, the crater formed on the Moon’s eastern edge sometime between April 11 and May 22, 2024, after a comet or asteroid the size of a three- to six-story building hit the surface.
 
The crash left a crater, 728 feet wide, that spans the length of two football fields. And at 141 feet deep, the crater could fit three vertically stacked yellow school buses.
 
Scientists estimate that an impact of this magnitude happens on the Moon about once in a century or even longer.

Moon takes some hits

For more than 17 years, LRO has been circling the Moon and using its seven instruments to map the topography, surface composition, temperature, and radiation environment there. The spacecraft’s team has identified at least 1,000 new impact craters throughout the mission and flagged 100,000 more surface changes from an object smashing into the Moon or from the debris that flung out after.

With no atmosphere to slow them or burn them up, space rocks and other objects easily reach the lunar surface. Most are much smaller compared to the object that carved out McGetchin crater. The smallest craters scientists can distinguish from LRO images are about 30 feet wide, the length of a three-story building laid on its side, made by rocks about 43 inches wide, the size of a monster-truck tire. Scientists estimate that impacts of this scale produce about 140 new craters across the Moon each year. But most new ones are made by microscopic projectiles that leave holes too small to identify in orbital images.

With its numerous instruments, the spacecraft can observe changes to the lunar surface that aren’t apparent in the LROC images alone. After the crater was discovered, scientists working with LRO’s thermal instrument, Diviner, made follow-up observations of the site. They found a 4-mile-wide area around the crater that is about 16 degrees Fahrenheit cooler at night than its surroundings.

Reporting in a second paper Wednesday in the same journal, researchers say that the cooling happens because the impact fluffs up the regolith around the crater, making it less dense and therefore less able to retain heat.

The large extent of this “cold spot” is striking, scientists say, because it shows that impacts can modify the Moon’s surface far beyond the crater itself. These physical changes could affect how rover wheels interact with the surface, for instance.

Road to discovery

The LROC system collects images from about 60 miles above the Moon as LRO loops from pole to pole. The system includes two cameras that capture high‑resolution black‑and‑white images and one camera for moderate‑resolution multispectral images. Over the years and thousands of passes, scientists have built maps detailed enough to spot not only new craters, but also landslides, landers, seismic faults, and even hints of lava tubes.

LROC scientists regularly analyze close-up images of small portions of the Moon’s surface taken by the Narrow-Angle Camera. Using these images, they look for changes that are typically less than 30 feet across. But every few years the team searches for large (wider than 150 feet) features by creating global Moon maps and comparing them to older versions.

That’s what Wagner was doing on Oct. 24, 2025, when he came across McGetchin. Using images from LROC’s Wide-Angle Camera, which captures broad views with pixels the size of football fields, he stacked hundreds of “before” and “after” frames with software designed to highlight change. Anything that stayed the same turned gray while anything different showed up as bright or dark patches.

While the process sounds straightforward, spotting real craters requires a lot of manual work. The software flags every tiny shift in lighting or shadow, generating hundreds of false alarms. For this reason, Wagner typically verifies the software, looking for small fuzzy halos around pixel‑wide bright points, which indicate splashes of regolith around a new crater.

Spanning hundreds of pixels, McGetchin stood out immediately. “It was by far the most obvious impact debris pattern I’ve ever seen in one of these images,” Wagner said.

After his discovery, scientists turned to the Narrow-Angle Camera, which takes much sharper views at about 3 feet per pixel. This camera’s close-up images, taken as LRO flew over the impact site again, revealed the crater size, shape, and how the surrounding terrain was affected. These images also helped researchers estimate the size and force of the rock fragment that formed the new crater, details that are expected to appear in a future paper.

Banner image caption: A zoomed-in view of the Moon, with debris around McGetchin crater visible as a white spot circled by a dark halo just right of center of the image (marked with black arrows). This is the view that Robert Wagner saw on Oct. 24, 2025, during a routine data-quality check. Wagner is an image processing specialist for NASA’s Lunar Reconnaissance Orbiter Camera, a system of three cameras. Using images from the Wide-Angle Camera (WAC), which captures broad views with pixels the size of American football fields, he stacked hundreds of images captured by WAC over the last several years with software designed to highlight change. Anything that stayed the same is gray; anything that changed showed up as bright or dark patches. The stripes in the image are due to slight changes in lighting between the older and newer images. This image composite shows an area of the Moon approximately 900 miles across.

University of Bern simulations and ESA Hera observations point to one non-destructive asteroid impact as the source of Deimos’ southern depression and dusty surface.

The post A Single Asteroid Impact May Have Shaped Mars’ Moon Deimos appeared first on Curiosmos.

Dr. Stephen Kane from the University of California, Riverside and colleagues offer a tidy explanation for one of the Solar System’s enduring puzzles: why Venus, so similar to Earth in size and mass, has no moon at all.

The post New Study Explains Why Venus Has No Moon appeared first on Sci.News: Breaking Science News.

In April, the world watched as four humans circled the Moon for the first time in over 50 years with NASA’s Artemis II mission. On Saturday, Sept. 19, the public is invited to look up again with NASA events across the country, including the International Observe the Moon Night celebration held at NASA’s Goddard Space Flight Center Visitor Center in Greenbelt, Maryland.

International Observe the Moon Night is an annual celebration that brings people together to learn about the Moon and explore our connection to Earth’s nearest celestial neighbor. Since the program began in 2010, people around the world have participated through lunar observations, hands-on activities, artwork, music, and more.
 
At NASA Goddard, this year’s celebration will highlight the agency’s ongoing exploration of the Moon, including the historic Artemis II mission. Visitors can peer behind the scenes to learn more about what it took to make Artemis II’s journey around the Moon a success and discover how Goddard scientists and engineers are helping advance our understanding of the Moon, solar system, and beyond.
 
The event will run from 6 p.m. to 9 p.m. EDT.
 
Throughout the event at NASA Goddard, visitors can take part in interactive hands-on activities, create artwork and crafts, and capture selfies at a photo kiosk. Telescopes will also be set up outside (depending on weather), giving attendees an opportunity to observe the Moon and other astronomical objects up close. Inside the Visitor Center, guests can even see a real Apollo 14 Moon rock on display.

• At 6:30 p.m., Dr. Amanda Nahm, planetary scientist at NASA Headquarters, will explore the lunar science and Moon joy from Artemis II.
• At 7:30 p.m., Ernie Wright, scientific visualizer at NASA Goddard, will offer a more technical look at how scientists use real data to create videos and visualizations of the Moon.

The event will also offer a chance to learn more about the groundbreaking research happening at NASA Goddard as scientists work to unlock the secrets of the Moon with missions like the Lunar Reconnaissance Orbiter (LRO) and explore our solar system and the universe beyond.
 
International Observe the Moon Night at Goddard is free and family friendly. Registration is not required, although registering in advance will help the Visitor Center team plan for the event. The event will take place rain or shine, and free parking is available at the Visitor Center.
 
Additional event details, including registration, accessibility and other logistics: https://www.nasa.gov/goddard/visitor-center/events-and-programs/.
 
For people who cannot travel to Greenbelt, there are opportunities to participate in International Observe the Moon Night from all around the planet. Join lunar observers around the world by observing the Moon with friends and family, attending a virtual event or finding an event in your area. Learn more and register your participation at go.nasa.gov/ObserveTheMoon.
 
International Observe the Moon Night is sponsored by NASA’s LRO mission and the Solar System Exploration Division of NASA’s Goddard Space Flight Center, with support from many partners. The celebration is a way for people to pause and look up at our future destination, as NASA prepares for deep space missions to the Moon and beyond.
 
To learn about NASA’s Artemis program, visit:
https://www.nasa.gov/artemis
 
To learn about LRO, visit:
https://www.nasa.gov/lro

The Moon may have emerged largely intact within hours of the colossal impact that shaped its birth. Earth has an unusually large moon for a planet of its size and position in the solar system, yet scientists still do not fully understand how that companion came to exist. Now, researchers from the Southwest Research Institute [...]

The Solar System’s smallest planet has contracted by nearly 19 km (12 miles) across, as crater debris masked telltale wrinkles on its surface, according to new research led by the German Aerospace Center’s Institute of Space Research.

The post Mercury Has Shrunk Even More than Planetary Scientists Thought appeared first on Sci.News: Breaking Science News.

Mercury has been slowly shrinking for billions of years. But scientists studying the smallest planet in the solar system may have overlooked just how dramatic that transformation has been because some of the evidence has literally been buried.

A new study suggests Mercury’s battered, crater-covered surface has concealed a significant fraction of the faults created as the planet cooled and contracted. After accounting for those hidden geological structures, researchers estimate Mercury may have shrunk by as much as 7.2 miles (11.6 kilometers) in radius—up to 30% more than previous estimates based on the same tectonic record.

The findings could alter models of how Mercury’s interior evolved and raise an interesting possibility beyond the planet itself. For instance, scientists may also be underestimating how much other rocky worlds, particularly the Moon, have contracted.

“Combined with the contractional strain map from Broquet and Andrews-Hanna (2026a), we show that radial contraction may have been underestimated by 10%–30%,” researchers write. “Our radial contraction correction should be considered as a lower bound.”

In the study published in Geophysical Research Letters, researchers led by Dr. Gaku Nishiyama of the German Aerospace Center (DLR) examined a longstanding mystery in Mercury’s geology.

As a rocky planet loses heat, its interior contracts. Much like the skin of a drying fruit, the planet’s rigid exterior must accommodate a shrinking interior, producing faults and enormous cliff-like features known as lobate scarps, along with wrinkle ridges and other shortening structures.

Scientists therefore use the crustal shortening recorded by these structures as a geological ruler to determine how much Mercury has contracted.

The problem is that those structures aren’t distributed across Mercury the way scientists might expect.

If cooling caused the entire planet to contract, the resulting deformation should be comparatively widespread. Instead, previous mapping has revealed regions filled with large scarps alongside enormous areas where surprisingly few contractional structures have been identified.

Dr. Nishiyama and his colleagues investigated whether at least part of that discrepancy could be an illusion created by Mercury’s extraordinarily battered surface.

Mercury’s Craters May Be Hiding Its Wrinkles

The researchers constructed a global map of Mercury’s surface roughness using topographic measurements acquired from NASA’s MESSENGER mission and a global digital terrain model produced from spacecraft imagery.

They then compared that roughness with previously cataloged tectonic structures.

Findings showed that fault scarps and other shortening structures were preferentially identified in smoother terrain, while rougher regions contained substantially fewer detectable structures. The relationship remained apparent across geographic scales extending to roughly 93 miles or about 150 kilometers.

That is counterintuitive because tectonic ridges themselves create topographic roughness. If roughness and plate movements were unrelated, areas with scarps might be expected to be slightly rougher than the surrounding terrain.

Instead, the researchers found the opposite.

One explanation is evident around relatively young impact craters such as Rachmaninoff. Large impacts blasted enormous quantities of debris across the surrounding landscape, producing thick blankets of material and secondary craters. In some locations, long tectonic structures appear to lose relief as they approach these deposits—consistent with the older structures being progressively hidden under impact material.

Other faults may still exist but become difficult to recognize against heavily cratered terrain. Once the surrounding topography becomes rough enough, a weathered ridge only a little higher than the background landscape can effectively disappear into the geological noise.

There is also a third possibility.

Heavily cratered regions may contain thick, porous layers of broken rock called regolith. During planetary contraction, some deformation could be absorbed as pores collapse rather than producing large faults visible from orbit. Alternatively, deformation could create faults too small for current observations to resolve. The researchers say available evidence cannot yet rule out that possibility.

Mercury Could Have Shrunk by More Than 7 Miles

Whatever mechanism is responsible, Dr. Nishiyama and his colleagues argue the relationship creates a systematic bias, where scientists see more evidence of contraction where Mercury’s surface makes that evidence easier to preserve and identify.

The team developed a correction using comparatively smooth regions, where tectonic structures appear less affected by this bias.

Applied to an earlier global estimate of 5.2 miles (8.3 kilometers) of radial contraction, the correction increased Mercury’s estimated shrinkage to roughly 7.2 miles or about 11.6 kilometers.

Depending on which tectonic structures are included, the researchers estimate surface roughness could have caused previous calculations to underestimate Mercury’s contraction by roughly 10% to 30%. They also caution that their corrected figure may itself represent a lower limit.

Ultimately, Mercury’s shrinking surface effectively records what has happened deep inside the planet.

The amount of contraction constrains how quickly Mercury lost heat, the thickness of its insulating regolith, the abundance of heat-producing elements, and even the composition and freezing history of its enormous metallic core. The revised estimate, for example, favors models involving a thinner regolith and lower sulfur content in Mercury’s core than some previous estimates.

Scientists may soon get a much sharper look.

The ESA-JAXA BepiColombo mission’s laser altimeter will eventually measure Mercury’s topography at scales as small as about 330 feet or 100 meters, possibly revealing geological relationships that MESSENGER could not resolve.

And Mercury may not be the only world whose geological record has been hiding in plain sight.

The Moon’s highlands are even rougher than Mercury’s cratered plains—by roughly 40% at the little-over 6-mile (10-kilometer) scale examined by the researchers. Yet evidence suggests the Moon contracted less than some thermal models estimate. If rough terrain similarly hides lunar faults, part of that difference might reflect structures scientists haven’t been able to see.

In other words, Mercury’s missing wrinkles may expose a wider problem in planetary geoscience. The more battered an ancient world becomes, the more effectively its later surface can erase the visible record of what happened before it.

“Investigating roughness alongside tectonic landforms may therefore refine our understanding of the lunar thermal evolution as well,” researchers conclude. “Mars could also be subject to this roughness effect, while topographic smoothing due to fluvial and aeolian processes may introduce more complex correlation between surface roughness and shortening structures.”

Study: Nishiyama, G., Broquet, A., Tosi, N., Preusker, F., Stark, A., Hussmann, H., & Hauber, E. “Underestimation of Planetary Contraction Due to Obscuration by Surface Roughness: The Case of Mercury.” Geophysical Research Letters 53, (2026). 

Tim McMillan is a retired law enforcement executive, investigative reporter and co-founder of The Debrief. His writing typically focuses on defense, national security, the Intelligence Community and topics related to psychology. You can follow Tim on Twitter: @LtTimMcMillan.  Tim can be reached by email: tim@thedebrief.org or through encrypted email: LtTimMcMillan@protonmail.com 

A new study using data from a space mission suggests that most of Mercury’s crustal magnetic fields can be explained by iron and other magnetized rocks in the crust responding to the planet’s weak present-day core magnetic field, rather than from an ancient field, as had been inferred previously. Mercury is the only solar-system planet other than Earth to possess both a global magnetic field arising from its core and a crustal magnetic field resulting from rocks that were magnetized in either the present-day or an ancient core field. Present-day (induced) magnetization reveals the location and amount of iron in the crust, whereas ancient (remanent) magnetization records the planet’s dynamo history.

NASA’s MErcury, Surface, Space ENvironment, GEochemistry and Ranging (MESSENGER) mission observed the planet in 2011–2015. Data from the mission are allowing scientists to explore the strength and distribution of Mercury’s magnetic field. During the mission, a last-minute decision was made “to reduce the orbit altitude thereby allowing crustal fields to be detected” explains Lon Hood at the Lunar and Planetary Laboratory at the University of Arizona. He has worked extensively on Mercury’s crustal magnetism using the MESSENGER data but was not involved in the new study.

Crustal magnetism was expected to be “partly due to remanent magnetization dating from the time when the crustal sources formed in the planetary magnetic field,” Hood says. This interpretation is drawn from earlier analyses of the mission data. But a key challenge in understanding the crustal magnetic field remained – how to delineate the contributions of induced and remanent magnetization. Separating the relative contributions of ancient and present-day induced magnetization on the crustal magnetic field can reveal new ways of understanding the spatial abundance of magnetic rocks, variations of magnetic properties of crustal minerals, and the dynamo history of Mercury.

New insights from old data

The new study, led by Catherine Johnson at the University of British Columbia in Vancouver, uses field observations of Mercury’s crustal magnetic fields from MESSENGER to develop a magnetization model of the planet and identify sources of its magnetization. The researchers calculated the expected induced magnetization strength using the low-altitude observations with assumptions on the crustal thickness, magnetic mineralogy, iron content, and the present-day core field.

In line with previous studies, the researchers found that the largest magnetization strengths occur in the Caloris region, along with localized signals elsewhere. The spatial pattern of magnetization strength, however, does not consistently match the variation in near-surface iron content seen in MESSENGER spectroscopic data. Instead, magnetization strength correlates with crustal thickness, up to about 30 km, suggesting the magnetized rocks are concentrated within the upper part of the crust.

The researchers found that induced magnetization is relatively small, given the low iron content of the planet’s crust and its weak core field – about a hundred times weaker than Earth’s. Even so, they estimate that induced magnetization can fully account for the calculated magnetization strength across more than 85% of the area north of 38 °N. This assumes it extends through the crustal column to a depth of about 30 km, which means that no remanent magnetization is required to explain the observed crustal field over that majority of the mapped region. Areas where induced magnetization does not explain the observed crustal fields may be the result of iron delivered by ancient asteroid impacts, which would locally increase the induced magnetization. Elsewhere, a contribution from remanent magnetization may be required to explain the observed fields.

Towards better characterization

On Earth, the robust separation of induced and remanent magnetizations requires laboratory measurements of rock samples. For Mercury no such samples exist, so the magnetic properties of its crust must be inferred from satellite observations constrained by assumptions about the composition and magnetic behaviour of its rocks. The delineation in the new study depends on “assumptions about magnetic mineralogy that cannot be verified due to the lack of returned samples”, says Hood.

Better characterization of the crust’s low-field magnetic susceptibility – currently inferred from a limited number of laboratory measurements on meteorites and minerals believed to resemble Mercury’s crust – can advance our understanding of Mercury’s crustal fields. Better core-field models and higher-resolution iron maps from the European–Japanese BepiColombo mission could help. This mission comprises two spacecraft that launched in 2018 and is expected to run until 2029.

However, Hood says “there are no current plans for either spacecraft to approach near enough to the planet to detect or map more of the crustal magnetic field”. Although the spacecraft will eventually descend below 100 kilometres, giving us a first look at the southern hemisphere. Indeed, we may have a long wait before we have the complete picture because Hoods says, ” there are no plans to obtain samples of Mercury’s crustal rocks, which are needed to definitively determine the origin of the crustal magnetization”.

The researchers report their findings in PNAS.

The post Mercury may not need an ancient dynamo to explain its magnetic crust appeared first on Physics World.

The European Space Agency is moving "full steam ahead" with development of a robotic mission to Venus after NASA officials determined they were unlikely to fulfill a commitment to provide a US-built radar instrument for the spacecraft, the mission's project scientist said.

The European orbiter, named Envision, will map the Venusian surface at 10 times higher resolution than the last radar mission sent to Venus by NASA in the 1990s. The planet is enshrouded in a blanket of thick clouds of sulfuric acid, rendering its mysterious surface unseen by optical cameras in orbit. Radar is the most effective way to penetrate the clouds of Venus to reveal the terrain below, and scientists will use Envision to look for signs of active volcanism.

NASA and ESA signed a memorandum of understanding in 2024 outlining their partnership on Envision. NASA agreed to supply a US-made synthetic aperture radar instrument, Envision's primary means of mapping the surface of Venus, along with providing tracking and communications support through NASA's Deep Space Network. In exchange, ESA would include US researchers on Envision's science team. Europe would build the Envision spacecraft and the rest of its science instruments and provide the launch on an Ariane 6 rocket.

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© ESA/Paris Observatory/VR2Planets

The European Space Agency is moving "full steam ahead" with development of a robotic mission to Venus after NASA officials determined they were unlikely to fulfill a commitment to provide a US-built radar instrument for the spacecraft, the mission's project scientist said.

The European orbiter, named Envision, will map the Venusian surface at 10 times higher resolution than the last radar mission sent to Venus by NASA in the 1990s. The planet is enshrouded in a blanket of thick clouds of sulfuric acid, rendering its mysterious surface unseen by optical cameras in orbit. Radar is the most effective way to penetrate the clouds of Venus to reveal the terrain below, and scientists will use Envision to look for signs of active volcanism.

NASA and ESA signed a memorandum of understanding in 2024 outlining their partnership on Envision. NASA agreed to supply a US-made synthetic aperture radar instrument, Envision's primary means of mapping the surface of Venus, along with providing tracking and communications support through NASA's Deep Space Network. In exchange, ESA would include US researchers on Envision's science team. Europe would build the Envision spacecraft and the rest of its science instruments and provide the launch on an Ariane 6 rocket.

Read full article

Comments

© ESA/Paris Observatory/VR2Planets

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The post What Is the Solar System? How Our Cosmic Neighborhood Took Shape appeared first on Curiosmos.

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