News Feeds

The Solar System’s hundreds of moons are like puzzle pieces. Together, they make a picture of all the forces that can create and modify them and the forces that shape our Solar System. One of them is Miranda, one of 28 known moons that orbit the ice giant Uranus. Miranda is its smallest major moon, at 471 km in diameter.

New research shows that this relatively small, distant moon may be hiding something: a subsurface ocean.

Miranda stands out from the other moons for one reason: its surface is a bizarre patchwork of jumbled terrain. There are cratered areas, rough scarps, and grooved regions. It may have the tallest cliff in the Solar System, a 20 km drop named Verona Rupes. Many researchers think its surface is deformed by tidal heating from gravitational interactions with some of the Uranus’ other moons.

New research in The Planetary Journal set out to explain Miranda’s jumbled geology. It’s titled “Constraining Ocean and Ice Shell Thickness on Miranda from Surface Geological Structures and Stress Modeling.” The lead author is Caleb Strom, a graduate student at the University of North Dakota.

“To find evidence of an ocean inside a small object like Miranda is incredibly surprising,”

Tom Nordheim, co-author and planetary scientist at the Johns Hopkins Applied Physics Laboratory

Scientists don’t have much to go on when it comes to Miranda. The only spacecraft to image it was Voyager 2 in 1986. Even then, the flyby was brief, and the spacecraft only imaged the moon’s southern hemisphere. But that was enough to reveal the moon’s bizarre and complex geological surface features. Miranda’s strange surface coronae attracted a lot of attention.

This figure from the study shows some of Miranda’s surface features. The moon is known for its coronae features, two of which are labelled here. Image Credit: Strom et al. 2024.

When the images were first received, scientists were baffled by Miranda’s complexity. Some called it a “patchwork planet,” and there was much healthy speculation about what created it. Attempts to understand the moon are still limited by the amount of data that Voyager 2 provided. However, modern scientists have access to a more powerful tool than scientists did in the 80s: computer models and simulations.

Strom and his co-researchers used a computer model to work backward from Miranda’s current surface. They started by mapping Miranda’s surface features, including its cracks, ridges, and unique trapezoidal coronae, and then reverse-engineered it. They tested different models of the moon’s interior to see what could account for the varied surface.

This simple schematic shows the four-layer model Strom and his co-researchers worked with. Image Credit: Strom et al. 2024.

The model that best matched the surface was one where Miranda had a vast ocean under its surface some 100-500 million years ago. The icy crust is probably 30 km thick or less, and the ocean could be up to 100 km thick.

“Our results show that a thin crust (?30 km) is most likely to result in sufficient stress magnitude to cause brittle failure of ice on Miranda’s surface,” the authors explain in their research. “Our results also suggest the plausible existence of a ?100 km thick ocean on Miranda within the last 100–500 million yr.”

“To find evidence of an ocean inside a small object like Miranda is incredibly surprising,” said Tom Nordheim, a planetary scientist at the Johns Hopkins Applied Physics Laboratory (APL) in Laurel, Maryland, a study co-author, and the principal investigator on the project that funded the study. “It helps build on the story that some of these moons at Uranus may be really interesting — that there may be several ocean worlds around one of the most distant planets in our solar system, which is both exciting and bizarre.”

Tidal heating is responsible for this, and it came from gravitational relationships between Miranda and Uranus’ other moons. Moons tug on each other, and when they’re in an orbital resonance with one another, where each moon’s period around a planet is an exact integer of the others’ periods, those tugs are amplified. These forces can periodically deform the moons, and as they’re squeezed, they heat up, keeping subsurface oceans warm and liquid.

Miranda and other moons of Uranus were likely in resonance in the past, which could’ve created surface fractures and related terrain.

A digital elevation model (DEM) of Miranda’s Inverness Coronae. The relative elevation ranges from 0 km (purple) to 4 km (red). Image Credit: Beddingfield et al. 2022.

However, resonances don’t last forever, and the researchers think that some time ago, Miranda left orbital resonance, and its interior began to cool. They don’t think it’s completely cooled yet because if the ocean had completely frozen, it would’ve expanded and displayed telltale surface cracks. So, the interior ocean likely still exists but is probably much thinner than in the past. “But the suggestion of an ocean inside one of the most distant moons in the solar system is remarkable,” Strom said.

Nobody predicted that Miranda would have an ocean. As far as scientists could tell, it was a frozen ball. But they’ve been wrong about moons before.

Researchers used to think that Saturn’s moon, Enceladus, the most reflective object in the Solar System, was just a ball of ice. After all, its surface is smooth and clearly frozen solid. However, the Cassini mission showed us that it may not be totally frozen. There’s a bevy of evidence that Enceladus has a warm ocean under a layer of ice.

This false-colour image of the plumes erupting from Enceladus is easily recognizable to many. Enceladus and Miranda are similar in important ways. Could Miranda also be geologically active? Image Credit: NASA/ESA

“Few scientists expected Enceladus to be geologically active,” said co-author Alex Patthoff. “However, it’s shooting water vapour and ice out of its southern hemisphere as we speak.”

Since both Enceladus and Miranda are roughly the same size and may have similar ice shells, it increases the chances that Miranda also has an ocean. Other moons, like Saturn’s Europa, may also be icy ocean moons. Now, scientists think these moons and their warm oceans are the best targets in the search for life in our Solar System.

Other recent research suggests that Miranda could be more like Enceladus than thought. One 2023 study showed that the moon may be releasing material into space like Enceladus does. The ESA and NASA are both sending probes to Jupiter to study Europa and other potential ocean moons. Should we expand that search to distant Uranus and its small moon Miranda?

An artist’s impression of Uranus and its five largest moons (innermost to outermost): Miranda, Ariel, Umbriel, Titania and Oberon. A 2023 paper showed that Ariel and/or Miranda could be releasing material into space. Image Credit: NASA/Johns Hopkins APL/Mike Yakovlev

“We won’t know for sure that it even has an ocean until we go back and collect more data,” said study co-author Nordheim. “We’re squeezing the last bit of science we can from Voyager 2’s images. For now, we’re excited by the possibilities and eager to return to study Uranus and its potential ocean moons in depth.”

For now, all we have is decades-old Voyager 2 data. However, the data and the computer models the team employed shed new light on Miranda.

“We interpret the tidal stress model results to indicate that at some point in Miranda’s geologic past, it experienced an intense heating event that resulted in a thin crust (?30 km). Such a thin crust would also have resulted in a ?100 km thick ocean to account for the molten part of the hydrosphere. This thin ice crust and thick ocean could have allowed for intense tidal stress leading to significant geologic deformation in the form of brittle deformation at Miranda’s surface,” the authors explain.

“In conclusion, our results suggest that Miranda could have had a subsurface ocean in the geologically recent past from an intense heat pulse, consistent with dynamical modelling results of previous studies,” they conclude.

The post There’s Another Ocean Moon Candidate: Uranus’ Tiny Moon Miranda appeared first on Universe Today.

https://traffic.libsyn.com/secure/sciencesalon/mss481_Edward_Goldberg_2024_10_29.mp3 Download MP3

The United States as Global Liberal Hegemon: How the U.S. Came to Lead the World examines America’s role as the global liberal hegemon. Using a historical analysis to understand how the United States came to serve as the world leader, Goldberg argues why the role of a liberal hegemon is needed, whether the United States has the ability to fulfill this role, and what the pitfalls and liabilities of continuing in this role are for the nation. He also considers the impact that this role on the global stage has for the country as well as individual citizens of the United States. Goldberg argues that the United States’s geographic location away from strong competitors, it’s role as the dominant economy for much of the 20th century, and its political culture of meritocracy all contributed to the United States taking this role in the 1940s. He also argues that the role of liberal hegemon has shifted to include not only being the international policeperson but also to be the world’s central banker, a role that at this time only the United States can fill.

Edward Goldberg is a leading expert in the area of where global politics and economics intercept. He teaches International Political Economy at the New York University Center for Global Affairs where he is an Adjunct Assistant Professor. He is also a Scholarly Practitioner at the Zicklin Graduate School of Business of Baruch College of the City University of New York where he teaches courses on globalization. With over 30 years of experience in international business and as a former member of President Barack Obama’s election Foreign Policy Network Team, Dr. Goldberg is the author of Why Globalization Works For America: How Nationalist Trade Policies Destroy Countries, and The Joint Ventured Nation: Why America Needs A New Foreign Policy. He is a much-quoted essayist and public speaker on the subjects of Globalization, European-American relations, U.S.-Russian and China relations. He has commented on these issues on PBS, NPR, CBS, Bloomberg, and in The New York Times, The Hill, and the Huffington Post. His new book is The United States as Global Liberal Hegemon: How the U.S. Came to Lead the World.

Shermer and Goldberg discuss:

“In the 1940s, when America anointed itself hegemon, somewhat like in Great Britain in the nineteenth century, American foreign policy was largely, aside from Harry Truman and a few others, dominated by a group of men who generally all went to similar prep schools and graduated from Princeton, Yale, or Harvard. This has changed drastically. If there is one common domestic thread in American post-World War II history, it is how American society and political life has become noticeably more diverse.”

• The 2024 presidential election is the first time Americans are voting on whether the U.S. should remain the so-called “leader of the free world” – or just go it alone as Donald Trump suggests. Even in the late 1930s, the heyday of isolationism, isolationism never appeared on the ballot. In fact in the presidential election of 1940, the Republican candidate Wendel Wilkie was an internationalist.
• What are the benefits to American citizens to continue in this role? What are the costs? And why can’t another nation or some institution play this role?
• Does the U.S. need allies to be successful or are relationships/institutions like NATO “obsolete” as Trump has stated?
• Why does there need to be a global leader or as Secretary of State Blinken said, an organizer? Is there any logic for instance to Donald Trump’s statement that he would “encourage Russia to do whatever the hell they want?”
• As the world faces new globalized communal problems, climate change, pandemics, financial contagion, etc., is the U.S. political culture capable of leading the world against these more abstract threats?
• Secretary of State Blinken’s statement, “Whether we like it or not, the world does not organize itself,” I look at why the United States is the only country capable of organizing the world, of being the liberal hegemon.
• the world’s central banker, the financial fireman of the world, a position at this time only the United States can fulfill.
• why a liberal hegemon is needed. Why can’t the United Nations organize the world or be the cop?
• The United States was the only major nation whose birth was influenced by the philosophical enlightenment movement. Thus, it has a very different view of the role of government. In America, the government was created not to watch over the individual welfare of its citizens but to guarantee their fundamental rights and liberties. That perspective emphasizes the individual over the community. Does America’s political culture, based on an aggrandized view of the eighteenth-century enlightenment theory of individual rights, hinder its ability to lead in the twenty-first century?
• Foreign governments have been trying to influence American foreign policy since the time of George Washington.
• disastrous mistakes like Vietnam and Iraq
• The March of Folly
• are the rewards of hegemony worth the price for the American citizen? $1.120 trillion the United States spent on defense in 2022. This expenditure created approximately 800,000 civilian jobs and 1.3 million active-duty jobs. But could these funds have created larger economic growth if applied to other areas?
• U.S. has defense treaties with 51 countries plus independent security understandings with others.
• Is the Iowa farmer aware that the reason their soybeans can be shipped safely around the world is because of the protection of the United States Navy?
• Roosevelt State of the Union address to Congress January 6, 1941: “No realistic American can expect from a dictator’s peace international generosity, or return of true independence, or world disarmament, or freedom of expression, or freedom of religion-or even good business … Such a peace would bring no security for us or for our neighbors. Those, who would give up essential liberty to purchase a little temporary safety, deserve neither liberty nor safety.”
• The United States has agreed to treaties obligating it to the defense of 51 countries:
  • 28 countries in NATO, which is essentially a defense umbrella for Canada and most of Europe
  • 18 through the Rio Treaty that applies to most of Central and South America
  • ANZUS Treaty with Australia and New Zealand
  • A bilateral treaty with Japan
  • A bilateral treaty with South Korea
  • A bilateral treaty with the Philippines.
• The theory behind most of these treaties derived from the lessons of World War I and II and especially the isolationist period between those two wars. Essentially, the underlying idea for these agreements is to halt aggression early rather than letting it metastasize and potentially overcome the United States.

If you enjoy the podcast, please show your support by making a $5 or $10 monthly donation.

Researchers have developed an electrochemical reactor that has the potential to drastically reduce energy consumption and cost for direct air capture.

Simulations suggest that when a quantum battery shares a quantum state with the device it is powering, the device can gain more charge than was stored in the battery to begin with

Simulations suggest that when a quantum battery shares a quantum state with the device it is powering, the device can gain more charge than was stored in the battery to begin with

In some recent years, the Amazon biome released more carbon than it absorbed, and further degradation could make it a permanent shift

Saturn’s moon, Titan, is an anomaly among moons. No other moons have surface liquids, and aside from Earth, it’s the only other Solar System object with liquids on its surface. However, since Titan is so cold, the liquids are hydrocarbons, not water. Titan’s water is all frozen into a surface layer of ice.

New research suggests that under the surface, Titan is hiding another anomaly: a thick crust of methane.

The evidence for the methane comes mostly from craters. Observations have found few confirmed impact craters on the frigid moon, and the ones that have been observed are hundreds of meters shallower than the same-sized craters on other moons. If Titan’s crust was rock, the craters should be much deeper.

The new research, published in The Planetary Science Journal, is titled “Rapid Impact Crater Relaxation Caused by an Insulating Methane Clathrate Crust on Titan.” Lauren Schurmeier, from the Hawai’i Institute of Geophysics and Planetology at the University of Hawai’i at Manoa, is the lead author.

Titan stands apart from other moons for multiple reasons. Unlike any other natural satellites in the Solar System, it has a thick atmosphere. Its atmosphere is about 50% more dense than Earth’s and extends about 600 km into space. A haze made of complex organic molecules called tholins gives the atmosphere its characteristic orange colour. The atmosphere is so thick that it blocks optical light, making Titan’s surface features nearly inscrutable.

The Cassini spacecraft has given us our best looks at Titan. It used radar and infrared instruments to see the moon’s surface. The small Huygens probe that went to Saturn with Cassini was released into Titan in 2005 to study the atmosphere and surface. It’s thanks to Huygens that we have our best images of Titan’s surface.

The new research suggests a link between Titan’s unusual atmosphere, its shallow surface craters, and a layer of methane in the moon’s crust. The methane keeps the underlying layer of ice convective by insulating it and helps impact craters rebound quickly and remain shallow.

There’s no consensus on how many craters Titan has because its surface is veiled behind its thick atmosphere, but there is some data on the craters.

This graph shows crater candidate counts binned by latitude regions and certainty level. Craters of certainty level 1 have more lines of evidence pointing toward an impact crater origin; certainty level 4 is the least certain. Image Credit: Schurmeier et al. 2024.

The research centres on the fact that Titan displays few craters and that the ones we do see are shallow. This sets it apart from other moons.

These are Cassini SAR (synthetic aperture radar) images of Titan’s impact craters. Arrows indicate potential forms of crater modification processes, including dunes and sands (purple), channels (blue), and significant crater rim erosion (pink). Afekan crater is one of Titan’s largest impact craters at 115 km. Jupiter’s moon, Ganymede, which is about the same size as Titan, has way more craters, including 20 that are larger than Afekan. Image Credit: NASA/ Cassini

“This was very surprising because, based on other moons, we expect to see many more impact craters on the surface and craters that are much deeper than what we observe on Titan,” said lead author Schurmeier. “We realized something unique to Titan must be making them become shallower and disappear relatively quickly.”

A handful of processes have been proposed to explain Titan’s diminishing craters. Liquid hydrocarbon rainfall, aeolian sand infill, and topographic relaxation induced by insulating sand infill have all been discussed. “Here, we propose an additional mechanism: topographic relaxation due to an insulating methane clathrate crustal layer in Titan’s upper ice shell,” the authors write.

This simple schematic of Titan’s interior (not to scale) shows a methane clathrate crust over a convecting ice shell. The methane clathrate can insulate the ice below and keep it convective. That convection could explain why Titan’s craters are so few and so shallow. Image Credit: Schurmeier et al. 2024.
 

There’s very little new information coming from Titan, so researchers have to work with what they have. To try to understand its shallow craters, the researchers built a computer model. They used it to try to understand how Titan’s topography might respond to impacts if a layer of methane clathrate was trapped under the surface. A clathrate is a substance where one type of molecule is trapped within a structure of molecules of another type. In this case, methane is trapped in water ice.

Methane’s insulating properties are key.

“Methane clathrate is stronger and more insulating than regular water ice,” said Schurmeier. “A clathrate crust insulates Titan’s interior, makes the water ice shell very warm and ductile, and implies that Titan’s ice shell is or was slowly connecting.”

With their model, they tested clathrate crusts that were 5, 10, 15, or 20 km thick. They used craters that were 40, 85, 100, and 120 km in diameter, each with two initial depths based on Ganymede’s crater diameters and depths. The result?

“We find that all clathrate crustal thicknesses result in rapid topographic relaxation despite Titan’s cold surface temperature,” the researchers write. “The 5 km thick clathrate crust can reproduce nearly all of the observed shallow depths, many in under 1000 yrs.”

They also found that a 10 km clathrate crust can reproduce Titan’s observed crater depths over geologic timescales. “If relaxation is the primary cause of the shallow craters, then the clathrate thickness is likely 5–10 km thick,” they write.

Across all simulations, most of the crater relaxation occurred in 1,000 years. “This finding suggests that thin clathrate crusts cause crater shallowing in a geological instant, similar to a fast-flowing terrestrial glacier,” the authors explain. It could certainly explain why none of Titan’s craters are deep.

The researchers point out a couple of caveats, though. They assumed that Titan’s initial craters had depths similar to Ganymede’s. They could’ve formed at different depths and shapes. Their model also didn’t include heat generated by the impact itself or account for an impact-triggered discontinuity in the methane clathrate layer. “These thermal and dynamic changes might alter the morphological evolution of the crater,” they write.

Juno captured this image of Ganymede in July 2022. The moon’s impact craters are easily visible, including the crater Tros, which is prominent below the center at left. Image Credit: NASA/JPL-Caltech/SwRI/MSSS/Kevin M. Gill

This research adds to Titan’s mystery and our fascination with the unusual moon. It also adds another element to comparisons with Earth. Earth and Titan both have surface liquid and are the only two objects in the Solar System that do. Earth also has methane clathrates in its polar regions.

“Titan is a natural laboratory to study how the greenhouse gas methane warms and cycles through the atmosphere,” said Schurmeier. “Earth’s methane clathrate hydrates, found in the permafrost of Siberia and below the arctic seafloor, are currently destabilizing and releasing methane. So, lessons from Titan can provide important insights into processes happening on Earth.”

In the end, their results are clear: “We conclude that if crater relaxation is the primary cause of Titan’s unexpectedly shallow craters, then the clathrate crust is 5–10 km thick,” the authors write.

The post Titan May Have a Methane Crust 10 Km Thick appeared first on Universe Today.

By applying an electric field, the movement of microswimmers can be manipulated. Scientists describe the underlying physical principles by comparing experiments and theoretical modeling predictions. They are able to tune the direction and mode of motion through a microchannel between oscillation, wall adherence and centerline orientation, enabling different interactions with the environment.

By applying an electric field, the movement of microswimmers can be manipulated. Scientists describe the underlying physical principles by comparing experiments and theoretical modeling predictions. They are able to tune the direction and mode of motion through a microchannel between oscillation, wall adherence and centerline orientation, enabling different interactions with the environment.

Researchers designed tiny particles that can be implanted at a cancer tumor site, where they deliver two types of therapy: heat and chemotherapy.

Mechanical engineers designed a 3D-printed femur that could help doctors prepare for surgeries to repair bones and develop treatments for bone tumors. The study, which focused on the middle section of the bone, establishes 3D-printing parameters for a femur for use in biomechanical testing. Researchers said more studies will be needed before the technology could be available for widespread use.

Approximately 50 percent of global final energy consumption is dedicated to heating. Yet, the utilization of solar power in this sector remains relatively low compared to fossil energy sources. An inherent problem limiting the widespread usage of solar energy is the intermittency of its direct availability. A promising solution comes in the form of molecular solar energy storage systems.

Scientists highlighted the potential for ultrasound to treat some of the more complex health conditions affecting the human brain.

Asteroids that regularly fly between Earth, Venus and Mars could provide radiation shielding for human missions to explore neighbouring planets

We get about a quarter of our calories from snacks and new research shows that this isn't necessarily bad for us. Done right, snacking can boost our health

A research team has developed a deep skin-stimulating LED mask which has been verified in clinical trials to improve dermis elasticity by 340%.

A study developed a new technique to accurately analyse the properties of cancer cells and the surrounding tissue at the level of individual cells. This innovation enables a more comprehensive assessment of prognoses and treatment responses in the head and neck cancers, and paves the way for more accurate diagnostics.

Using state-of-the-art microscopy and simulation techniques, an international research team systematically observed how iron atoms alter the structure of grain boundaries in titanium. They were in for a surprise.

New research shows that not all standing positions in airport smoking lounges are created equal. Scientists found that the thermal environment and positioning of smokers influences how particles settle in the room. Additionally, smokers seated farther from ventilation inlets experience the lowest levels of pollution in the room. The researchers created a smoking room using computational models and placed heated and unheated manikins in the room to simulate smokers. They also modeled the ventilation system with three exhaust air diffusers.

Researchers overcame the tradeoff between plastic toughness and degradability by developing plastics with movable crosslinks. The crosslinks both increased toughness by over eight times and increased enzymatic degradability by over twenty times compared with those of a reference plastic without movable crosslinks. These advanced biodegradable plastics bring us one step closer to achieving a resource-circulating society.