Underwater Structure Discovered And Disappeared

When figuring out a solution, it helps to approach a problem from every possible angle. The same can be said for climate change-induced ice melt in the Antarctic, which is why the International Thwaites Glacier Collaboration (ITGC) programmed an automated underwater vehicle (AUV) — nicknamed "Ran" — to dive into the cavity of the Dotson Ice Shelf, located near Thwaites Glacier in West Antarctica.

Over the course of 27 days, the submarine traveled more than 600 miles—including 10 miles directly into the cavity itself—to both figure out the mechanics of how glaciers melt faster near strong underwater currents and glimpse the topography of this all-important ice shelf.

What the experts behind this submersible found is that the attributes along the western part of the ice shelf differ greatly with the eastern portion, which is thicker and therefore melting more slowly.

The Ran AUV also produced high resolution maps of the underside of the Dotson Ice Shelf that revealed strange tear-drop features, icy plateaus, and detailed erosion patterns. The results of the study were published in the journal Science Advances.

"We have previously used satellite data and ice cores to observe how glaciers change over time," Anna Wåhlin, the lead author of the study, said in a press statement. "By navigating the submersible into the cavity, we were able to get high resolution maps of the ice underside. It’s a bit like seeing the back of the Moon."

Unlike glaciers, which rest on land, ice shelves are actually a part of the ocean. They sort of act like a buttress that keeps ice on land from flowing into the ocean and raising sea levels, and are are vitally important to these polar ecosystem as a result. And because these shelves rest on the ocean, it’s possible to get under them.

But just because it’s possible doesn’t mean it’s easy.

The 20-foot-long Ran submersible used pulsed sound waves (advanced multibeam sonar) on the ice to map its features, but because of its subantarctic location, Wåhlin and her team couldn’t communicate with the AUV or track its movements with GPS. After 14 missions—some lasting a couple hours and others stretching longer than a day—Ran mapped around 50 square miles of ice, and the structures imaged were more complex than anyone imagined.

"The mapping has given us a lot of new data that we need to look at more closely," Wåhlin said in a press statement. "It is clear that many previous assumptions about melting of glacier undersides are falling short. Current models cannot explain the complex patterns we see. But with this method, we have a better chance of finding the answers."

One of the team’s discoveries is that the different melt rates between east and west portions of the Dotson Ice Shelf could be explained by a phenomenon known as the modified Circumpolar Deep Water (mCDW), which is when Pacific and Indian Ocean water mix with other local water masses that impact the ice base. This data was supplemented by Ran’s measurements of these underwater currents, as well as the high melting rates of fractures that run through the glacier.

Although the team’s initial mission was to study the nearby Thwaites glacier, the environment proved too difficult to access. The Dotson Ice Shelf, however, served as the perfect candidate to test the equipment and methods, according to The New York Times. These surveys were conducted in 2022, and the team returned earlier this year to see what changes to the ice shelf had occurred. That’s when Wåhlin and her team’s worst fears were realized—Ran didn’t emerge at the pre-planned rendezvous point. The team suspects that the AUV either ran aground or became the target of some curious seals.

"Although we got valuable data back, we did not get all we had hoped for. These scientific advances were made possible thanks to the unique submersible that Ran was," Wåhlin said in a press statement. "This research is needed to understand the future of Antarctica’s ice sheet, and we hope to be able to replace Ran and continue this important work."

Read More......

Bermuda's Floating Mystery Solved

For millions of years, the archipelago of Bermuda has floated, an apparent anomaly in the Atlantic.

Now, seismologists have finally solved the mystery of why this volcanic island, inactive for over 30 million years, hasn’t sunk back into the ocean.

The answer lies not in hot magma plumes, but in a massive, never-before-seen "rock raft" deep beneath the seabed. Beneath Bermuda’s oceanic crust lies a rock layer 20 kilometers (12.4 miles) thick.

"We identify features associated with a ∼20 km thick layer of rock below the oceanic crust that has not yet been reported," the researchers from the Carnegie Institution for Science in the US wrote in the study paper.

"This thick layer beneath the crust likely was emplaced when Bermuda was volcanically active 30–35 million years ago and could support the bathymetric swell," it added.

Interestingly, the study suggests that the Bermuda swell is not supported by a hot mantle plume or a deep thermal anomaly, as is commonly assumed for other large bathymetric swells.

Volcanic islands, like the famed Hawaiian chain, are typically buoyed by hot, active magma plumes pushing up the Earth’s crust.

But Bermuda’s last major eruption was roughly 30 million years ago. Geologically, it should have subsided and vanished long ago as the underlying lithosphere cooled.

Yet, the island remains, sitting atop a bathymetric swell — a large, persistent bulge in the ocean floor.

This unique structure likely accounts for Bermuda’s continued elevation, preventing its subsidence long after the volcanic activity ceased tens of millions of years ago.

Using seismic data from a permanent station on the island, researchers analyzed recordings of large global earthquakes.

By studying how seismic waves suddenly changed speed, they created a detailed image of the Earth’s layers up to 31 miles (50 km) beneath Bermuda.

Surprisingly, researchers found a unique, massive geological layer wedged between the oceanic crust and the rigid upper mantle.

Measuring 12 miles in thickness, this layer is unlike anything previously observed beneath an island located in the middle of a tectonic plate.

Moreover, this immense layer acts like a "buoyant raft" because it is less dense than the surrounding rigid upper mantle, thereby supporting the island’s elevation.

Read More......

Solar Storms Threatened Starlink Satellites

There is a team of scientists that expressed concern has warned that the space congestion problem is in danger of spiralling out of control, describing our current situation as a "House of Cards".

Individual satellites within mega-constellations, such as SpaceX’s Starlink, must perform an increasing number of collision-avoidance maneuvers each year.

According to scientists, solar storms could trigger Kessler Syndrome — a scenario in which satellites collide, leading to a cascading, destructive event in Earth’s orbit.

A Federal Communications Commission (FCC) filing in 2023 showed that SpaceX’s Starlink satellites had to make 50,000 collision avoidance maneuvers over the previous four years.

That same year, Hugh Lewis, a professor of astronautics at the University of Southampton in the UK, calculated that, if trends continued, Starlink satellites would have to perform roughly a million maneuvers every six months by 2028.

This leaves little margin for error. Ultimately, space is becoming increasingly congested, and we are edging closer to the cascading destructive scenario known as Kessler Syndrome. This could ultimately prevent spacecraft from reaching orbit, as there would be too great a risk of collision with small space debris.

Now, a team at Princeton University has warned that solar storms could be the tipping point that leads to a Kessler Syndrome scenario. In a pre-print, they explain that solar storms heat the atmosphere, increasing atmospheric drag. This means that more fuel is required to maintain orbits and perform evasive maneuvers.

Read More......

Cube-Shaped Skull Discovered In Ancient Site

Nearly every corner of the world contains archaeological evidence of the ancient practice of artificial cranial deformation. The Huns of Central Asia are a well-known example, but so are the Hirota people of ancient Japan, the Maya of Central America, and even members of the peasant class in Toulouse, France, around the end of the 19th century.

Today, some cultures in the Democratic Republic of the Congo and Vanuatu in the South Pacific still practice the tradition.

Most of these examples—both historical and contemporary—form pointed skulls by binding an infant’s head while the skull bones fuse (typically up until the age of two). It’s not incredibly common to see a cube-shaped skull, but the Instituto Nacional de Antropología e Historia (INAH) recently reported one such discovery in the Mexican state of Tamaulipas near the Balcón de Montezuma—an archaeological site occupied by various ethnic groups between 650 B.C.E and 1200 C.E.

One of these communities, around the year 400 C.E., contained roughly 90 houses and a variety of artifacts. As the archaeologists sifted through these finds, they discovered what appeared to be a parallelepiped, or cube-shaped, skull. Artificial skull deformation was a common practice among the Maya, but hasn’t been documented in this particular site.

"Not only was intentional cranial deformation identified for the first time for this type of site, but also a variant with respect to the models recognized in Mesoamerica, not reported, until now, in the area," biological anthropologist Jesús Ernesto Velasco González said in a translated press statement. Velasco González noted that similar deformations occurred at the El Zapotal archaeological site in Veracruz, located further south along the Gulf of Mexico, so scientists tried to piece together potential migration leaks. However, those didn’t quite pan out.

"Stable oxygen isotope studies in collagen and bioapatite samples from bone and teeth, a technique used to infer the geographic origin of the second individual's skeletal remains, indicate that he was born, lived, and died in this part of the mountains," Velasco González said in a press statement. "Therefore, the results rule out a direct mobility relationship with the groups of El Zapotal or those further south."

The reasons why the people of Pre-Columbian Mesoamerica—or any people, for that matter—practiced skull formation are almost as varied as the people groups themselves. Sometimes it was a marker of social hierarchy, sometimes it was a religious rite, and sometimes it was just for aesthetics. Although the health effects are debated, it’s largely believed that this practice doesn’t decrease the size of the skull, and as such, health impacts are mostly negligible (though some research has asserted that the practice could impact cognitive or memory function).

Read More......

Why Are Dolphins Swimming with Orcas?

There is a pod of Pacific white-sided dolphins sighted off the coast of British Columbia cooperating with orcas, a traditional enemy that’s better known for taking out great white sharks than friendly interaction.

Scientists say they have documented the dolphins and a local population of killer whales known as Northern Resident orcas teaming up to hunt the orcas’ staple food: salmon. Though other groups of orcas feast on dolphins, Northern Residents do not. Still, it is the first time this type of cooperative behavior has been documented between the two marine mammals, researchers reported.

"Seeing them dive and hunt in sync with dolphins completely changes our understanding of what those encounters mean," said Sarah Fortune, Canadian Wildlife Federation chair in large whale conservation and an assistant professor in Dalhousie University’s oceanography department. Fortune was the lead author of the study, which published in the journal Scientific Reports.

To witness the dolphins and orcas interacting, the researchers captured drone footage as well as underwater video by attaching suction tags to the orcas that were equipped with cameras and hydrophones.

Their footage showed that the killer whales traveled toward the dolphins and followed them at the surface level. The underwater footage revealed that the killer whales were also following dolphins on their dives of up to 60 meters (197 feet), where the orcas were able to prey on Chinook salmon.

Though light levels are low at those depths, Fortune said cameras picked up the killer whales catching salmon, with clouds of blood billowing from their mouths, and hydrophones picked up the crunch of a kill.

To understand better what was happening, the researchers also eavesdropped on the echolocation clicks made by dolphins and orcas, which allow animals to navigate and sense their environment by listening to the returned echoes of the noises they make.

"We can look at the characteristics of these clicks to infer whether a whale is actively chasing a prey for a fish and also whether it may have caught the fish," Fortune said.

The researchers recorded 258 instances of dolphins and orcas interacting between 15 and 30 August 2020.

They found that all the whales that interacted with dolphins also engaged in killing, eating and searching for salmon.

Put together, the data Fortune and her colleagues collected suggested that the killer whales, fearsome predators able to take on great whites and whale sharks several times their size, were essentially using the dolphins as scouts.

"By hunting with other echolocating animals like the dolphins, they might be increasing their acoustic field of view, providing greater opportunity to detect where the salmon are. That’s sort of the prevailing thought here," she explained. Using dolphins in this way would also allow the orcas to conserve energy, with salmon often hiding at depths to try and avoid predators such as orcas.

But what do dolphins get out of the interactions?

The video Fortune and her colleagues collected showed that once the orcas caught their prey and shared it with the pod, the dolphins were quick to eat the leftovers.

But salmon isn’t a core part of a dolphin’s diet, so greater access to food likely wasn’t the sole motivation, Fortune said. By hanging out with the orcas, dolphins likely gain protection from other orca pods that pass through the area and hunt dolphins.

Read More......