Astronomy

Distant Titan is an oddball in the Solar System. Saturn’s largest moon—and the second largest in the entire Solar System—has an atmosphere denser than Earth’s. It also has stable lakes and seas of liquid hydrocarbons on its surface.

New research shows that waves on these seas are eroding Titan’s coastlines.

The research is “Signatures of Wave Erosion in Titan’s Coasts,” and it’s published in Science Advances. The lead author is Rose Palermo, an MIT graduate and research geologist at the U.S. Geological Survey.

In 2007, the Cassini spacecraft spotted lakes and seas of liquid hydrocarbons, mostly methane and ethane, on Saturn’s moon Titan. Titan and Earth are the only two bodies in the Solar System known to have surface liquids. Scientists have only Cassini data from Titan to work with, and they’ve been poring over the data in an effort to understand this strange world.

The moon’s seas are one of the most intriguing features throughout the entire Solar System. But they’re difficult to observe because of the thick atmosphere. Researchers have wondered if waves shape the coastlines, but there are conflicting signs about the nature of the seas. They could be rough, or they could be smooth. A paper from 2014 suggested that transient features in Titan’s northern sea, Ligeia Mare, could be waves.

But there’s no certainty.

“We found that if the coastlines have eroded, their shapes are more consistent with erosion by waves than by uniform erosion or no erosion at all.”

Rose Palermo, lead author, U.S. Geological Survey

“Some people who tried to see evidence for waves didn’t see any, and said, ‘These seas are mirror-smooth,'” lead author Palermo said in a press release accompanying the research. “Others said they did see some roughness on the liquid surface but weren’t sure if waves caused it.”

It seems likely that there would be waves on Titan. To investigate this question, researchers at MIT compared Titan’s shorelines to shorelines on Earth to see if they match.

The seas and lakes on Titan look much like some on Earth. They appear to be flooded valleys and depressions. But scientists are uncertain if these bodies of water are eroding their coastlines like those on Earth. “Spacecraft observations and theoretical models suggest that wind may cause waves to form on Titan’s seas, potentially driving coastal erosion, but the observational evidence of waves is indirect, and the processes affecting shoreline evolution on Titan remain unknown,” the authors write in their paper.

The problem is that there’s no reliable way to connect shoreline morphology directly to the mechanisms that shape it, even on Earth. To try to understand how erosion affects Titan’s coastlines, the researchers started with Earth. They examined how different coastal erosion mechanisms shape Earth’s coastlines, then applied the framework to Titan.

There are basically two types of coastal erosion: wave-driven erosion and uniform erosion. Each type produces different coastlines.

Wave erosion is driven by wind and produces a change proportional to the strength of the waves. Waves are usually stronger the farther they travel before they hit a coast. Wave erosion creates long, smooth stretches of coast where the coast is fully exposed and bays in protected areas where less erosion occurs. The distance the wind can blow to generate waves on a particular water body before striking a coast is called ‘fetch.’

“Wave erosion is driven by the height and angle of the wave,” Palermo explained. “We used fetch to approximate wave height because the bigger the fetch, the longer the distance over which wind can blow and waves can grow.”

Uniform erosion is different. It doesn’t rely on mechanical wave action. The compositional differences between Earth and Titan are apparent when it comes to uniform erosion. “Titan’s crust consists mainly of water ice, but its surface solids may also include heavy hydrocarbon molecules, such as benzene, that are soluble in liquid methane and ethane, such that the liquid lakes and seas may slowly dissolve the solid coasts of the north polar terrain,” the authors explain in their research.

Over a long enough period of time, uniform erosion occurs at the same rate in all locations, producing distinct morphological features: shorelines that are generally smooth even inside bays with sharp headlands that punctuate them.

“Here, we test the hypothesis that coastal erosion has shaped Titan’s seas by investigating whether coastline shapes are most consistent with wave-driven erosion, uniform erosion, or no coastal erosion,” the authors write.

This figure from the research illustrates how the two types of erosion would shape shorelines. The images are based on simulated Titan landforms and shorelines. A shows the initial condition of Titan’s water bodies, where rivers carved out channels, and rising seas flooded them. B shows the morphology that wave erosion would produce, where the erosion rate depends on fetch. C shows the morphology that Uniform erosion would produce, where the erosion is uniform in all locations. Darker blue indicates deeper water and lighter yellow indicates higher land. Image Credit: Palermo et al. 2024.

The different morphological features produced by wave-driven erosion and uniform erosion are obvious. Wave-driven erosion tends to smooth exposed sections of the coastline where fetch is large and preserve the coastline where fetch is small inside embayments.

Uniform erosion is different. It widens embayments and smooths out small-scale roughness on the coastline regardless of fetch. Headlands are the exception, which sharpen into thick-necked points that stick out into the main basin.

“We had the same starting shorelines, and we saw that you get a really different final shape under uniform erosion versus wave erosion,” said co-author Taylor Perron, Professor of Earth, Atmospheric and Planetary Sciences at MIT. “They all kind of look like the Flying Spaghetti Monster because of the flooded river valleys, but the two types of erosion produce very different endpoints.”

Titan’s Ligeia Mare is the second largest liquid body on Titan. The researchers say that its coastline appears to be altered by wave-driven erosion. Image Credit: By NASA/JPL-Caltech/ASI/Cornell – http://photojournal.jpl.nasa.gov/catalog/PIA17031, Public Domain, https://commons.wikimedia.org/w/index.php?curid=26294960

“We found that if the coastlines have eroded, their shapes are more consistent with erosion by waves than by uniform erosion or no erosion at all,” Perron said.

But these are just simulations, and they have to be tested rigorously. The team’s next step was to quantify these differences in the real world. The researchers explain that they “developed a technique focusing on local relationships between shoreline roughness and fetch area” to understand and quantify the differences. Specifically, they quantified what they call “roughness” to differentiate wave-driven erosion from uniform erosion. “Simply put, a lower roughness means a smoother stretch of shoreline compared to the rest of the lake, and a higher roughness means a comparatively rough stretch of shoreline,” they write.

This figure from the research shows roughness and fetch area for two of Titan’s seas: Kraken Mare and Ligeia Mare. C and D show roughness for each sea. E and F show the normalized fetch area, assuming waves are fetch-limited. Fetch-limited means waves continue to grow as long as the fetch length increases. G and H show normalized fetch area assuming a saturation fetch length of 20 km. That means that waves only grow up to a certain fetch length and then saturate. In that case, the system is saturation-limited, and the “fetch length in all directions is truncated to a maximum value.” Image Credit: Palermo et al. 2024.

The researchers say that “… shoreline roughness and normalized fetch area can be used to fingerprint wave-driven and uniform erosion and distinguish them from a coastline consisting only of flooded river valleys,” as shown in the first image.

So, what does this all boil down to?

“Our results suggest that the coastlines of Titan’s largest liquid bodies are most consistent with shorelines that have been modified by wave erosion and river incision,” the researchers write in their paper. They analyzed four coastlines and found a less than 5% probability of uniform erosion in a saturation-limited scenario and a less than 20% probability of uniform erosion in a fetch-limited scenario. That leaves wind-driven erosion as the most likely cause of erosion, which seems to confirm that Titan’s lakes and seas experience waves. “Therefore, our results suggest that the largest seas and lakes are not consistent with erosion by uniform processes (i.e., dissolution), as previously hypothesized for some of Titan’s landscapes,” they conclude.

That’s the scientific way of presenting their results, and their paper is like part of a long conversation with other scientists. In the press release, they state their conclusion more plainly for the rest of us.

“We can say, based on our results, that if the coastlines of Titan’s seas have eroded, waves are the most likely culprit,” said Perron, Professor of Earth, Atmospheric and Planetary Sciences at MIT. “If we could stand at the edge of one of Titan’s seas, we might see waves of liquid methane and ethane lapping on the shore and crashing on the coasts during storms. And they would be capable of eroding the material that the coast is made of.”

“Waves are ubiquitous on Earth’s oceans. If Titan has waves, they would likely dominate the surface of lakes,” says Juan Felipe Paniagua-Arroyave, associate professor in the School of Applied Sciences and Engineering at EAFIT University in Colombia, who was not involved in the study.” It would be fascinating to see how Titan’s winds create waves, not of water, but of exotic liquid hydrocarbons.”

The next step is to determine how strong Titan’s winds have to be to create coastal erosion. The researchers also hope to decipher which directions the wind is predominantly blowing from.

“Titan presents this case of a completely untouched system,” Palermo said. “It could help us learn more fundamental things about how coasts erode without the influence of people, and maybe that can help us better manage our coastlines on Earth in the future.”

The post Lake Shorelines on Titan are Shaped by Methane Waves appeared first on Universe Today.

Around the world, people celebrated the June 20 solstice in a variety of ways as Earth's north pole reached its greatest tilt towards the sun.

Virgin Galactic announced a private mission with three researchers, which will fly no earlier than 2026 aboard the new Delta class of aircraft.

Astronomers have pressed rewind on a cosmic video of the solar neighborhood, tracing the origins of young star clusters within 3,000 light-years of the Sun.

The post Astronomers Trace the Family Tree of Stars Clustered in the Solar Neighborhood appeared first on Sky & Telescope.

A preview of Marvel Comics' "Predator versus Black Panther" miniseries coming this summer.

Scientists observed leeches jumping like striking snakes, resolving long-standing debate

An urn found in a tomb in Spain contained the cremated remains of a man, a gold ring and about 5 litres of liquid, which has been identified as now-discoloured white wine

An urn found in a tomb in Spain contained the cremated remains of a man, a gold ring and about 5 litres of liquid, which has been identified as now-discoloured white wine

Artificial intelligence has taken the world by storm lately. It also requires loads of band-end computing capability to do the near-miraculous things that it does. So far, that “compute,” as it’s known in the tech industry, has been based entirely on the ground. But is there an economic reason to do it in space? Some people seem to think so, as there has been a growing interest in space-based data centers. Let’s take a look at why.

Space-based data centers have several advantages over ground-based ones. The first and most obvious is the near-unlimited amount of space in space. Second, there are plenty of potential options for novel power and cooling technologies that can’t exist back on Earth. Third, using a space-based data center as a relay point for information could cut down on lag in data transfer between continents. Let’s look at each in turn.

One of the significant constraints for data centers is space – they require large amounts of it, and it is expensive in the areas where they are most needed (i.e., next to large population centers). The tech giants have massive budgets associated with real estate for data centers, and that amount will only continue to grow as their computational requirements increase. On the other hand, building a modular data center in space, with each launch adding additional computing power, is a reasonable way to infinitely expand a company’s hardware resources without the constraint of a physical location.

OrbitsEdge is a start-up company focusing on building space-based data centers. Here’s a video describing their business model.
Credit – OrbitsEdge YouTube Channel

Data centers would also have access to novel power and cooling technologies in space. They could utilize solar panels directly attached to them to harness unlimited green energy, and ones in a high enough orbit could be powered effectively all the time, no matter weather conditions or Earth’s rotation. Power satellites run off a similar idea, and the underlying technology is already there; it hasn’t been applied to this use case yet.

Many data centers also use water cooling systems. While water is heavy and expensive to launch into orbit, plenty of asteroids have enough water on them to supply millions of data centers with all the cooling they need. A recent paper from researchers in South Africa looked at this process and found several asteroids with relatively close trajectories that could supply orbiting data centers with enough water to last centuries.

Space-based data centers could also allow for fast transmission between two points on the globe without sending data over a complicated path from one continent to another. Directly linking two computers is easier if they have a line of sight to the same relay point, such as a data center floating around the Earth. Using that data center to relay information between the two, similar to what Starlink currently does with satellite internet technology, would solve latency problems between far-away locations.

Diagram of the collaboration between Axiom, Kepler, and Skyloom for an orbital data center.
Credit – Axiom Space

But there are also some hurdles. Data transfer rates on satellites aren’t up to speed with modern ground-based technologies, though that is consistently improving every year thanks to efforts like Starlink. Getting the hardware into orbit poses an obvious challenge and expense. However, that bar might be better lower with the continual development of Starship and its low-cost launch capability. Finally, coordinating across different governments, especially regarding wireless bandwidth, can be tricky, but without that coordination, the ability to talk across borders is severely limited.

None of those limitations are insurmountable; technologists and investors seem to realize that. As our own Alan Boyle reported in March, a company called Lumen Orbit raised $2.4 million only three months after being founded to bring data centers to space. Axiom Space, which we’ve mentioned in several articles in the last few years, is also partnering with Kepler Space and Skyloom to develop the world’s first functional space-based data center.

With this increased interest, it seems only a matter of time before some of the computing power that is enabling the AI and computing revolution makes its way into orbit. But for now, the question remains: who will be the first one to do it?

Learn More:
GeekWire – Lumen Orbit emerges from stealth and raises $2.4M to put data centers in space
Periola, Alonge, & Ogudo – Space-Based Data Centers and Cooling: Feasibility Analysis via Multi-Criteria and Query Search for Water-Bearing Asteroids Showing Novel Underlying Regular and Symmetric Patterns
UT – Starlinks are Easily Detected by Radio Telescopes
UT – Watch a Real-Time Map of Starlinks Orbiting Earth

Lead Image:
Artist’s conception of a Lumen Orbit space-based data center.
Credit – Lumen Orbit

The post Could We Put Data Centers In Space? appeared first on Universe Today.

Earth's oft-squabbling nations will need to set aside their differences, at least for a while, when a big, dangerous asteroid puts our planet in its crosshairs.

The energy of moon-forming can have a big say in whether large or doomed smaller moons are built.

With a heat dome baking the eastern U.S., emergency departments in New England and the Midwest have seen a spike in heat-related cases

Sizzling summer days can be a dangerous time to be outside. Here’s what to think about before heading into the heat and how to stay safe

“HuskyWorks,” a team from Michigan Technological University’s Planetary Surface Technology Development Lab, tests the excavation tools of a robot on a concrete slab, held by a gravity-offloading crane on June 12 at NASA’s Break the Ice Lunar Challenge at Alabama A&M’s Agribition Center in Huntsville, Alabama. Led by Professor Paul van Susante, the team aimed to mimic the conditions of the lunar South Pole, winning an invitation to use the thermal vacuum chambers at NASA’s Marshall Space Flight Center to continue robotic testing.

Analyzing 1,504 supernovae into the distant universe, astronomers have shown the clearest evidence yet for cosmological time dilation as predicted by Einstein

Yesterday, the first Ariane 6 rocket to launch into space went through its last full ‘wet dress rehearsal’ at Europe’s Spaceport in French Guiana – it provided an exciting sneak peek of what’s to come, stopping just a few seconds before engine ignition and of course, lift-off.

Snapped from lunar orbit in 1968 by NASA astronaut Bill Anders, who died this week at age 90, 'Earthrise' is perhaps the most iconic image of our planet ever taken.

The James Webb Space Telescope has unlocked another achievement. This time, the dynamic telescope has peered into the heart of a nearby star-forming region and imaged something astronomers have longed to see: aligned bipolar jets.

JWST observing time is in high demand, and when one group of researchers got their turn, they pointed the infrared telescope at the Serpens Nebula. It’s a young, nearby star-forming region known for being the home of the famous Pillars of Creation. (The Hubble Space Telescope made the pillars famous, and the JWST followed that up with its own stunning image.)

But these researchers weren’t focusing on the Pillars. As a nearby star-forming region, Serpens Nebula is a natural laboratory to study how stars form and to try to answer some outstanding questions about the process. The JWST delivered.

A team of astronomers from the USA, India, and Taiwan examined the region and published their results in a paper titled “Why are (almost) all the protostellar outflows aligned in Serpens Main?” The lead author is Joel Green from the Space Science Telescope Institute.

Stars form when Giant Molecular Clouds of hydrogen collapse. They start out as protostars, objects that haven’t begun fusion yet and are still acquiring mass. As they grow, gas from the cloud gathers in a swirling accretion ring around the star. As it moves, the gas heats up and emits light.

As the cloud collapses into a protostar, some of the energy is converted into angular momentum and the young star spins. For the young star to keep acquiring mass, some of the spin needs to be removed. That happens as the swirling accretion disk emits some of the gas from bipolar jets, also called protostellar outflows. They’re part of how stars regulate themselves as they grow, and they come from the young star’s poles, perpendicular to the spin. The magnetic fields around the star drive the jets out of the poles.

This artist’s illustration shows a young protostar and its protostellar jets. Image Credit: NASA/JPL-Caltech/R. Hurt (SSC)

But there’s a lot more detail in the process and some outstanding questions. Stars don’t form in isolation; they usually form in clusters or groups, and there are intermingling magnetic fields at work. At only 1300 light-years away, Serpens Nebula is a good place to try to spy some of this detail. Until the JWST came along, the detail was hidden from even our most powerful telescopes, and astrophysicists were left to theorize with what they could observe.

“Star formation is thought to be partly regulated by magnetic fields with coherence scales of a few parsecs – smaller than Giant Molecular Clouds, but larger than individual protostars,” the authors write in their paper. “Magnetic fields likely play a key role in the collapse of cloud cores distributed in elongated structures called filaments.”

Cloud cores are the precursors to star clusters, and the filaments are filaments of gas inside giant molecular clouds. Cloud cores cluster along these filaments where the gas density is higher. Much of what goes inside these environments is shrouded by gas and dust, so theories were based on what astronomers were able to observe prior to the JWST.

“While theory often assumes idealized alignment of protostellar disks, cores, and associated magnetic fields, feedback may lead to misalignment on the smallest scales (1000 au) as the protostar evolves,” the authors write. To understand what happens when protostars form in these environments, astrophysicists wanted to know if the angular momentum in a group of stars that form together correlates with each other and with the magnetic field of the filament they form in.

The key to understanding this is the protostellar jets that come from young protostars since their direction is governed by magnetic fields. Protostellar outflows are a signature of young, still-forming stars, and when these outflows collide with the surrounding gas, they create “striking structures of shocked ionized, atomic, and molecular gas,” the authors write.

“Since the jets are likely accelerated and collimated by a rapidly rotating poloidal magnetic field in the inner star-disk system, they emerge along the stellar rotation axis and thus trace the angular momentum vector of the star itself,” the authors explain.

That leads us to the significance of the new JWST image of Serpens Nebula. The researchers found a group of young protostars in the Serpens Nebula with aligned jets. These stars are only about 100,000 years old, making them desirable observational targets in the effort to understand star formation.

This image from the NASA/ESA/CSA James Webb Space Telescope shows a portion of the Serpens Nebula, where astronomers have discovered a grouping of aligned protostellar outflows. These jets are signified by bright, clumpy streaks that appear red, which are shock waves from the jet hitting surrounding gas and dust. Here, the red colour represents the presence of molecular hydrogen and carbon monoxide. Image Credit: NASA, ESA, CSA, STScI, K. Pontoppidan (NASA’s Jet Propulsion Laboratory), J. Green (Space Telescope Science Institute)

The jets in a group of young protostars are usually misaligned. Previous research, including research based on JWST images, found only misaligned jets among groups of stars in the same clusters and clouds. Many things can misalign the jets in associated stars, but the outstanding question is if stars that form together start out with the same magnetic field alignment.

Webb found something different in the Serpens Nebula. The telescope found a group of 12 protostars whose jets are lined up with the magnetic field of the filament they formed in.

“The axes of the 12 outflows in the NW region are inconsistent with random orientations and align with the filament direction from NW to SE,” the researchers write in their paper. They say the probability of this happening randomly is extremely low. “We estimate <0.005% probability of the observed alignments if sampled from a uniform distribution in position angle,” they write.

The stars along the filament in the northwest region are aligned, but stars along other filaments in other regions of Serpens are not aligned.

“It appears that star formation proceeded along a magnetically confined filament that set the initial spin for most of the protostars,” the authors write in their conclusion. “We hypothesize that in the NW region, which may be younger, the alignment is preserved, whereas the spin axes have had time to precess or dissociate through dynamic interactions in the SE region.”

The JWST needed only two NIRCam images of the Serpens Nebula to answer a question that’s foundational to star formation. Its work won’t end here.

“We anticipate more detailed studies of star-forming filaments with JWST in the future,” the authors conclude.

The post The JWST Peers into the Heart of Star Formation appeared first on Universe Today.

This month, let's turn our attention to two celestial objects that can readily be seen even from bright cities. One is our nearest neighbor in space, while the other is a familiar pattern of stars.

As the patents on various weight-loss drugs near expiration, companies in India and China are vying to make lower-cost versions that will widen access to such treatments