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Scottish Crannog Centre Loch Tay

Researchers find artificial islands in Scotland to be much older than previous estimates

Ancient human beings in the northern part of British Isles did not live on dry land always. In Scotland, Ireland and Wales, there are several artificial islands which are present even to this day. Named as crannogs, these structures were built by prehistoric humans in the middle of rivers, lakes. It has not been known exactly when these structures were constructed. Normally, archaeologists have estimated it to be built around 800 BCE. However, recent evidence tells a different story. These structures could have been built much before than realised by researchers. The study has been published in Antiquity journal.

With the help of radiocarbon dating on sites located in the Outer Hebrides which is the Western Isles of Scotland, scientists have detected crannogs which date back as far as 3640-3360 BCE, which means that early human beings started building them 5500 years ago, even before the construction of Stonehenge.

Archaeologist Fraser Sturt, University of Southampton told that the crannogs are a symbol of monumental effort made thousands of years before to construct mini-islands by piling up rocks on loch bed. This is not the first time that researchers have thought about the Neolithic origins of the crannogs. Excavations carried out in the 1980s showed that they could date back thousands of years although for decades no such other specimens were located.

Things were shaken up when Chris Murray, former Royal Navy diver who resided in Scottish Isle of Lewis discovered a collection of very well preserved Early/Middle Neolithic pots on the loch bed while diving. Researchers then investigated Loch Arnish and other crannogs, many of which were not present in archaeological records with the help of Google Earth.

In total, the team discovered more than 200 Neolithic vessels made from ceramic, from five crannogs – which is an evidence of an extensive cultural practice we had not known about until now. Survey of these sites has demonstrated that crannogs had been a feature of the Neolithic and they may have been special locations, as found from evidence of deposition of material culture in the water.

According to the researchers, by the quantities of material identified and position of vessels in relation to islets, it is clear that the pots were intentionally deposited in water. Presence of soot on external surfaces and inner charred residues show that they were used before deposition. The amount of work gone into creating these giant structures make it clear that they had unique importance to the early community. The crannogs may have been reserved for important feasts, or mortuary rituals.

Dodgeball

Study finds out dodgeball to be a tool for oppression

According to a group of Canadian scientists, one of the most played games in gym classes, dodgeball is used as a tool for “oppression“. Professors from Canadian universities presented before the Congress of the Humanities and Social Sciences, Vancouver their paper on this subject where they mention that dodgeball is used to teach the students how to harm others.

Joy Butler, a professor of pedagogy and curriculum development at the University of British Columbia told over a phone interview that when an environment is created where students are told that it is alright to use the softball and hit whomever one likes, then the intention to harm others is present although subtle. Students are told it is okay to do it and this acts as an outlet for their inner aggression. He added that the classes of physical education should be a platform for students to have control over their anger, move beyond it rather than expressing it. Teachers should be telling students methods to control their aggression, not the opposite.

Scientists interviewed students of middle-schools regarding various physical education courses but they learnt repeatedly from some students that they hated dodgeball. They asked further and then matched the answers against the ideas given in Five Faces of Oppression, an article in Justice and the Politics of Difference authored by Iris Marion Young.

Here, Young says that the faces of oppression are, using benefits of other’s work for oneself, pushing a section of the society to a corner, taking away independence from that section of society, making the preferences of the ruling class as norm and making known to the marginalized section that they may be hurt. These points matched with the answers that the researchers got in the interviews.

Scientists found that the athletic students of the class formed their own groups to dominate over the rest of the class and whimsically created their rules. The true definition of competition is where evenly matched teams compete and all the students derive enjoyment from that. When asked in the class for creating a new game using the same ball and two goals, these same set of students developed their version without consulting their friends. This established that the dominating culture spilt to other sections of the physical education class.

Canadian schools are making positive changes in improving P.E classes. Teachers are taking steps to prevent girls from dropping out of their classes. Thus they should also focus in this area and make the curriculum holistic for all. This includes removing dodgeball.

A close up of human eye

Breakthrough in understanding how human eyes process 3D motion

Scientists at the University of York have revealed that there are two separate ‘pathways’ for seeing 3D motion in the human brain, which allow people to perform a wide range of tasks such as catching a ball or avoiding moving objects.

The new insight could help further understanding into how to alleviate the effects of lazy eye syndrome, as well as how industry could develop better 3D visual displays and virtual reality systems.

Much of what scientists know about 3D motion comes from comparing the ‘stereoscopic’ signals generated by a person’s eyes, but the exact way the brain processes these signals has not been fully understood in the past.

Scientists at the Universities of York, St Andrews, and Bradford have now shown that there are two ways the brain can compute 3D signals, not just one as previously thought.

Fast and slow signals

They found that 3D motion signals separate into two ‘pathways’ in the brain at an early stage of the image transmission between the eyes and the brain.

Dr Alex Wade from the University of York’s Department of Psychology said: “We know that we have two signals from our visual system that helps the brain compute 3D motion – one is a ‘fast’ signal and one is a ‘slow’ signal.

“This helps us in a number of ways, with our hand-eye coordination for example, or so that we don’t fall over navigating around objects. What we didn’t know was what the brain did with these signals to allow us to understand what is going on in front of our eyes and react appropriately.

“Using brain imaging technology we were able to see that these two 3D motion signals are separated out into two distinct pathways in the brain, allowing information to be extracted simultaneously and indicating to the visual system that it is encountering a 3D moving object.”

Lazy eye syndrome

The research team had previously shown that people with lazy eye syndrome might still be able to see ‘fast’ 3D motion signals, despite them having very poor 3D vision in general.  Now that scientists understand how this pathway works, there is the potential to build tests to measure and monitor therapies aimed at curing the condition.

Dr Milena Kaestner, who conducted the work as part of her PhD at the University of York, said: “We were also surprised to see a link between 3D motion signals and how the brain receives information about colour. We now believe that colour might be more important in this type of visual processing than we previously thought.

“The visual pathways for colour have been thought to be independent of signals about motion and depth, but the research suggests that there could be a connection in the brain between these three visual properties.”

Dr Julie Harris, from St Andrews University, said:  “Knowing more about our visual system, and particularly how motion, depth and colour could all be connected in the brain, could help in a number of research areas into what happens when these pathways go wrong, resulting in visual disturbances that impact negatively on people’s quality of life.”

Materials provided by University of York

Carbon Escape

An escape route for carbon

As many of us may recall from grade school science class, the Earth’s carbon cycle goes something like this: As plants take up carbon dioxide and convert it into organic carbon, they release oxygen back into the air. Complex life forms such as ourselves breathe in this oxygen and respire carbon dioxide. When microbes eat away at decaying plants, they also consume the carbon within, which they convert and release back into the atmosphere as carbon dioxide. And so the cycle continues.

The vast majority of the planet’s carbon loops perpetually through this cycle, driven by photosynthesis and respiration. There is, however, a tiny fraction of organic carbon that is continually escaping through a “leak” in the cycle, the cause of which is largely unknown. Scientists do know that, through this leak, some minute amount of carbon is constantly locked away and preserved in the form of rock for hundreds of millions of years.

Now, researchers from MIT and elsewhere have found evidence for what may be responsible for carbon’s slow and steady escape route.

In a paper published today in the journal Nature, the team reports that organic carbon is leaking out of the carbon cycle mainly due to a mechanism they call “mineral protection.” In this process, carbon, in the form of decomposed bits of plant and phytoplankton material, gloms onto particles of clay and other minerals, for instance at the bottom of a river or ocean, and is preserved in the form of sediments and, ultimately, rock.

Mineral protection may also explain why there is oxygen on Earth in the first place: If something causes carbon to leak out of the carbon cycle, this leaves more oxygen to accumulate in the atmosphere.

“Fundamentally, this tiny leak is one reason why we exist,” says Daniel Rothman, professor of geophysics in MIT’s Department of Earth, Atmospheric and Planetary Sciences. “It’s what allows oxygen to accumulate over geologic time, and it’s why aerobic organisms evolved, and it has everything to do with the history of life on the planet.”

Rothman’s co-authors on the paper include Jordon Hemingway, who led the work as a graduate student at MIT and the Woods Hole Oceanographic Institution and is now a postdoc at Harvard University, along with Katherine Grant, Sarah Rosengard, Timothy Eglinton, Louis Derry, and Valier Galy.

Burning dirt

Scientists have entertained two main possibilities for how carbon has been leaking out of the Earth’s carbon cycle. The first has to do with “selectivity,” the idea that some types of organic matter, due to their molecular makeup, may be harder to break down than others. Based on this idea, the carbon that is not consumed, and therefore leaks out, has been “selected” to do so, based on the initial organic matter’s molecular structure.

The second possibility involves “accessibility,” the notion that some organic matter leaks out of the carbon cycle because it has been made inaccessible for consumption via some secondary process. Some scientists believe that secondary process could be mineral protection — interactions between organic carbon and clay-based minerals that bind the two together in an inaccessible, unconsumable form.

To test which of these mechanisms better explains Earth’s carbon leak, Hemingway analyzed sediment samples collected from around the world, each containing organic matter and minerals from a range of river and coastal environments. If mineral preservation is indeed responsible for locking away and preserving carbon over geologic timescales, Hemingway hypothesized that organic carbon bound with clay minerals should last longer in the environment compared with unbound carbon, resisting degradation by foraging microbes, or even other forces such as extreme heat.

The researchers tested this idea by burning each sediment sample and measuring the amount and type of organic carbon that remained as they heated the sample at progressively higher temperatures. They did so using a device that Hemingway developed as part of his PhD thesis.

“It’s been hypothesized that organic matter that sticks to mineral surfaces will stick around longer in the environment,” Hemingway says. “But there was never a tool to directly quantify that.”

“Beating up a natural process”

In the end, they found the organic matter that lasted the longest, and withstood the highest temperatures, was bound to clay minerals. Importantly, in a finding that went against the idea of selectivity, it didn’t matter what the molecular structure of that organic matter was — as long as it was bound to clay, it was preserved.

The results point to accessibility, and mineral preservation in particular, as the main mechanism for Earth’s carbon leak. In other words, all around the world, clay minerals are slowly and steadily drawing down tiny amounts of carbon, and storing it away for thousands of years.

“It’s this clay-bound protection that seems to be the mechanism, and it seems to be a globally coherent phenomenon,” Hemingways says. “It’s a slow leak happening all the time, everywhere. And when you integrate that over geologic timescales, it becomes a really important sink of carbon.”

The researchers believe mineral protection has made it possible for vast reservoirs of carbon to be buried and stored in the Earth, some of which has been pressed and heated into petroleum over millions of years. At the Earth’s geologic pace, this carbon preserved in rocks eventually resurfaces through mountain uplift and gradually erodes, releasing carbon dioxide back into the atmosphere ever so slowly.

“What we do today with fossil fuel burning is speeding up this natural process,” Rothman says. “We’re getting it out of the ground and burning it right away, and we’re changing the rate at which the carbon that was leaked out is being returned to the system, by a couple orders of magnitude.”

Could mineral preservation somehow be harnessed to sequester even more carbon, in an effort to mitigate fossil-fuel-induced climate change?

“If we magically had the ability to take a fraction of organic matter in rivers or oceans and attach it to a mineral to hold onto it for 1,000 years, it could have some advantages,” Rothman says. “That’s not the focus of this study. But the longer soils can lock up organic matter, the slower their return to the atmosphere. You can imagine if you could slow that return process down just a little bit, it could make a big difference over 10 to 100 years.”

Materials provided by Massachusetts Institute of Technology

Pterodactyl fossil reconstitution

Researchers discover ancient creature to be able to fly right after birth

A recent breakthrough has found that pterodactyl which is an extinct flying reptile which is also known as pterosaurs has been found to have a remarkable ability that it can fly from birth. No other vertebrate living as of today or the ones who have lived in history has this kind of ability. There is no replicate for this creature till now and this revelation has had a profound impact on our understanding as to how pterodactyls have lived and in our understanding of the dinosaur world as a whole.

Pterodactyls were initially thought to able to take flight only when grown up to full size and assumptions were made based on fossilized embryos which were found in China. Dr David Unwin, a University of Leicester palaeobiologist and Dr Charles Deeming, a University of Lincoln zoologist who are specialized in study of pterodactyls and avian and reptilian reproduction were able to disprove this theory. There was a data comparison between the prenatal growth observed in birds and crocodiles in the early stage of development before hatching. Embryos found in China and Argentina had died just before they were hatched and provided the evidence that pterodactyls had the ability to fly from birth. The study has been published in Proceedings of the Royal Society B

The basic fundamental difference between the baby pterodactyls and baby birds and bats is that they are not given any parental care and had to look after themselves from birth and search for their feed. The ability to fly provided them with a life-saving mechanism with which they could protect themselves from the carnivores dinosaurs. This ability also proved to be one of their biggest killers, as the demanding and dangerous process of flight led to many of them dying at a very early age.

The research provides answers to some key questions surrounding these animals. Flaplings (baby pterodactyls) were known to fly and grow from birth and provides a possible explanation as to why they were able to achieve enormous wingspans which were larger than any historic or known species of bird or bat. Their wing finger is also known as manus digit IV had an early elongation and development, making them flight capable quite early in postnatal development. 

Further study is required to understand as to how they are able to carry out this process and with more developments raises more questions that were not posed earlier due to our limited understanding of the species. Complete and comparative anatomy can reveal novel developmental modes in the species of pterosaurs and how they can strikingly differ from birds and bats.

 

Daphnis saturn moon

NASA’s Cassini reveals new sculpting in Saturn’s rings

The beautiful planet, Saturn, popular for its complex rings was found to have more hidden details on intrinsic textures, colours and temperatures by NASA’s Cassini spacecraft.

The Cassini mission was concluded two years ago but the spacecraft’s trip to the ring planet is still transferring data to the planet about Saturn and its evolution through all these years. A paper which was published in the Science journal had followed four of the Cassini’s major instruments and observed the interaction between Saturn’s main rings and its tiny moons. Using the observational data of this, scientists have an elucidate picture of how Saturn’s rings are part of astrophysical disk processes that have been impacting the solar system.

Cassini also took into notice the fine details that were sculpted by masses within these rings. New maps that were released revealed how do chemical, colour, and temperature-related changes are, across the rings of Saturn.

The observation made by the spacecraft enabled scientists to attain a better grasp of the complexity of Saturn. It enabled the scientists to hypothesize the outer edge of the main rings of the ringed planet are formed due to impacts of the celestial bodies hitting the ring. This information also tells us that the rings were also shaped by material streams that are known to circle the planet. The close-ups of the rings highlights that the textures happen in belts which possess sharp boundaries and these belts are not connected to any of the planet’s rings.

The way these rings look tells that there is some peculiar characteristic particles present that affect whatever takes place between any two rings. Another mystery uncovered by Cassini’s VIMS( Visible and Infrared Mapping Spectrometer ) was that it detected unusually weak water-ice bands in the A ring’s outermost area. It was shocking to find the water-ice bands, because the vicinity is known to be very reflective, which could be a sign of less-contaminated ice and fortified water-ice bands.

The new spectral map that the scientists found also provided insights to the composition of the ring, confirming that ammonia ice and methane ice are not the contents but water ice is the major content of the planet’s rings. The drawback was that it could not spot any organic compounds.

According to the scientist of the Cassini project, Linda Spilker, it was like turning up the power by one more time to know what was inside the ring so that everyone could actually get to see it as an extra resolution which answered many questions but most tantalizing ones, however, remain.

watching tv

Study reveals everyday technology helps fight loneliness

The research, co-produced by the University of York and the loneliness charity WaveLength, looked at data collected from 445 people over two years and found that they rated their health more positively after being given new technology.

The study participants had an average age of 44 and over 50% had been homeless and experienced poor mental health.

Positive influence

Lead author of the study, Professor Marin Webber, from the Department of Social Work and Social Policy at the University of York, said: “The research shows that technology can have a positive influence on the life of someone who is lonely.

“The benefits of everyday technology are heightened for people who are at the greatest risk of suffering from loneliness. This includes people who are in a bad financial situation and experiencing poor physical and mental health.”

Clare, who is living in Kilburn, recently received a television from WaveLength after she left prison. Experiencing several health issues and disabilities means that she is now often housebound. Commenting on the difference her television has made, she explained: “I have found the TV to be invaluable as it is a real companion to me when I am bedbound and stops me from feeling lonely. I really enjoy tuning into my favourite programmes for entertainment and learning. The TV has made such a positive difference to my life.”

Connect

The report calls on policy makers to make funding available so that vulnerable people can purchase everyday technology and for free access to a minimum standard of broadband in order to connect greater numbers of people via smart televisions and tablet computers.

CEO of Wavelength, Tim Leech, said: “Our latest report shows that everyday media technology has a real role to play in helping people to feel less lonely. The research shows a statistically significant relationship between technology usage, a reduction in loneliness, and an increase in self-rated health. The results of this study should lead to a greater recognition of the valuable role technology can play in fighting loneliness, alongside other forms of support.”

Materials provided by Univerity of York

Electric Drop

A droplet walks into an electric field …

When a raindrop falls through a thundercloud, it is subject to strong electric fields that pull and tug on the droplet, like a soap bubble in the wind. If the electric field is strong enough, it can cause the droplet to burst apart, creating a fine, electrified mist.

Scientists began taking notice of how droplets behave in electric fields in the early 1900s, amid concerns over lightning strikes that were damaging newly erected power lines. They soon realized that the power lines’ own electric fields were causing raindrops to burst around them, providing a conductive path for lightning to strike. This revelation led engineers to design thicker coverings around power lines to limit lightning strikes.

Today, scientists understand that the stronger the electric field, the more likely it is that a droplet within it will burst. But, calculating the exact field strength that will burst a particular droplet has always been an involved mathematical task.

Now, MIT researchers have found that the conditions for which a droplet bursts in an electric field all boil down to one simple formula, which the team has derived for the first time.

With this simple new equation, the researchers can predict the exact strength an electric field should be to burst a droplet or keep it stable. The formula applies to three cases previously analyzed separately: a droplet pinned on a surface, sliding on a surface, or free-floating in the air.

Their results, published today in the journal Physical Review Letters, may help engineers tune the electric field or the size of droplets for a range of applications that depend on electrifying droplets. These include technologies for air or water purification, space propulsion, and molecular analysis.

“Before our result, engineers and scientists had to perform computationally intensive simulations to assess the stability of an electrified droplet,” says lead author Justin Beroz, a graduate student in MIT’s departments of Mechanical Engineering and Physics. “With our equation, one can predict this behavior immediately, with a simple paper-and-pencil calculation. This is of great practical benefit to engineers working with, or trying to design, any system that involves liquids and electricity.”

Beroz’ co-authors are A. John Hart, associate professor of mechanical engineering, and John Bush, professor of mathematics.

“Something unexpectedly simple”

Droplets tend to form as perfect little spheres due to surface tension, the cohesive force that binds water molecules at a droplet’s surface and pulls the molecules inward. The droplet may distort from its spherical shape in the presence of other forces, such as the force from an electric field. While surface tension acts to hold a droplet together, the electric field acts as an opposing force, pulling outward on the droplet as charge builds on its surface.

“At some point, if the electric field is strong enough, the droplet can’t find a shape that balances the electrical force, and at that point, it becomes unstable and bursts,” Beroz explains.

He and his team were interested in the moment just before bursting, when the droplet has been distorted to its critically stable shape. The team set up an experiment in which they slowly dispensed water droplets onto a metal plate that was electrified to produce an electric field, and used a high-speed camera to record the distorted shapes of each droplet.

“The experiment is really boring at first — you’re watching the droplet slowly change shape, and then all of a sudden it just bursts,” Beroz says.

After experimenting on droplets of different sizes and under various electric field strengths, Beroz isolated the video frame just before each droplet burst, then outlined its critically stable shape and calculated several parameters such as the droplet’s volume, height, and radius. He plotted the data from each droplet and found, to his surprise, that they all fell along an unmistakably straight line.

“From a theoretical point of view, it was an unexpectedly simple result given the mathematical complexity of the problem,” Beroz says. “It suggested that there might be an overlooked, yet simple, way to calculate the burst criterion for the droplets.”

A water droplet, subject to an electric field of slowly increasing strength, suddenly bursts by emitting a fine, electrified mist from its apex.

Volume above height

Physicists have long known that a liquid droplet in an electric field can be represented by a set of coupled nonlinear differential equations. These equations, however, are incredibly difficult to solve. To find a solution requires determining the configuration of the electric field, the shape of the droplet, and the pressure inside the droplet, simultaneously.

“This is commonly the case in physics: It’s easy to write down the governing equations but very hard to actually solve them,” Beroz says. “But for the droplets, it turns out that if you choose a particular combination of physical parameters to define the problem from the start, a solution can be derived in a few lines. Otherwise, it’s impossible.”

Physicists who attempted to solve these equations in the past did so by factoring in, among other parameters, a droplet’s height — an easy and natural choice for characterizing a droplet’s shape. But Beroz made a different choice, reframing the equations in terms of a droplet’s volume rather than its height. This was the key insight for reformulating the problem into an easy-to-solve formula.

“For the last 100 years, the convention was to choose height,” Beroz says. “But as a droplet deforms, its height changes, and therefore the mathematical complexity of the problem is inherent in the height. On the other hand, a droplet’s volume remains fixed regardless of how it deforms in the electric field.”

By formulating the equations using only parameters that are “fixed” in the same sense as a droplet’s volume, “the complicated, unsolvable parts of the equation cancel out, leaving a simple equation that matches the experimental results,” Beroz says.

Specifically, the new formula the team derived relates five parameters: a droplet’s surface tension, radius, volume, electric field strength, and the electric permittivity of the air surrounding the droplet. Plugging any four of these parameters into the formula will calculate the fifth.

Beroz says engineers can use the formula to develop techniques such as electrospraying, which involves the bursting of a droplet maintained at the orifice of an electrified nozzle to produce a fine spray. Electrospraying is commonly used to aerosolize biomolecules from a solution, so that they can pass through a spectrometer for detailed analysis. The technique is also used to produce thrust and propel satellites in space.

“If you’re designing a system that involves liquids and electricity, it’s very practical to have an equation like this, that you can use every day,” Beroz says.

Materials provided by Massachusetts Institute of Technology

Forschungsanlage XFEL

Phase change materials used in smartphones can increase data storage and energy efficiency

Phase change materials which are used in modern smartphones could lead to high storage capacities and increase energy efficiency. The data is recorded by switching the states between glassy and crystalline with the help of heat pulse. But till date, it has not been possible to understand what exactly happens at the atomic level.

A group of researchers from European XFEL, University of Duisburg-Essen, Germany and Lawrence Livermore National Laboratory(LLNL) described how X-ray free-electron laser at Linac Coherent Light Source (LCLS) was used to demonstrate a transition in chemical bonding mechanism, thus enabling the storage of data. The results can be used for the optimization of phase-change materials for efficient and improved data storage technologies. They also gave newer insights into the glass formation process. The study was published in the Science journal.

LLNL’s Stefan Hau-Riege, co-author of this paper told that as the current devices are used to store data more than ever, new techniques are needed for storing more information.

Phase-change materials made from elements such as antimony, tellurium and germanium are used for storing large amounts of data, efficiently and quickly. They are used as replacements for flash drives in current smartphones. These materials on applying electrical or optical pulse change from glassy to crystalline state. These two states represent the 0 and 1 in binary system for storing information. However, it has not been possible to understand this change at the atomic level until now.

Researchers used femtosecond X-ray diffraction technique for studying atomic changes when the materials switched states. The optical laser was first used for triggering the material to switch from crystalline to glassy state. The X-ray laser was used for taking images of the atomic structure. Researchers took more than 10,000 images for understanding the atomic sequence during the change of states.

For storing information in phase-change materials, they must be cooled very quickly form a glassy state without being crystallised. However for erasing the information, the same material has to be crystallised very quickly. Researchers found that when a liquid is cooled much below the melting point, it changes to form a low-temperature liquid which can be observed for a brief moment before it is crystallised. These liquids differ in behaviour as well as atomic properties. Liquid at a very high temperature has high atomic mobility for crystallisation. But below the boiling point, the chemical bonds get rigid and the disordered atomic structure of glass is held. This prevents the transformation and secures the data. This study explains how the switching process in modern technology can be both fast and reliable.

Europa

Table Salt Compound Spotted on Europa

A familiar ingredient has been hiding in plain sight on the surface of Jupiter’s moon Europa. Using a visible light spectral analysis, planetary scientists at Caltech and the Jet Propulsion Laboratory, which Caltech manages for NASA, have discovered that the yellow color visible on portions of the surface of Europa is actually sodium chloride, a compound known on Earth as table salt, which is also the principal component of sea salt.

The discovery suggests that the salty subsurface ocean of Europa may chemically resemble Earth’s oceans more than previously thought, challenging decades of supposition about the composition of those waters and making them potentially a lot more interesting for study. The finding was published in Science Advances on June 12.

Flybys from the Voyager and Galileo spacecrafts have led scientists to conclude that Europa is covered by a layer of salty liquid water encased by an icy shell. Galileo carried an infrared spectrometer, an instrument scientists use to examine the composition of the surface they’re examining. Galileo’s spectrometer found water ice and a substance that appeared to be magnesium sulfate salts—like Epsom salts, which are used in soaking baths. Since the icy shell is geologically young and features abundant evidence of past geologic activity, it was suspected that whatever salts exist on the surface may derive from the ocean below. As such, scientists have long suspected an ocean composition rich in sulfate salts.

That all changed when new, higher spectral resolution data from the W. M. Keck Observatory on Mauna Kea suggested that the scientists weren’t actually seeing magnesium sulfates on Europa. Most of the sulfate salts considered previously actually possess distinct absorptions that should have been visible in the higher-quality Keck data. However, the spectra of regions expected to reflect the internal composition lacked any of the characteristic sulfate absorptions.

“We thought that we might be seeing sodium chlorides, but they are essentially featureless in an infrared spectrum,” says Mike Brown, the Richard and Barbara Rosenberg Professor of Planetary Astronomy at Caltech and co-author of the Science Advances paper.

However, Kevin Hand at JPL had irradiated ocean salts in a laboratory under Europa-like conditions and found that several new and distinct features arise after irradiation, but in the visible portion of the spectrum. He found that the salts changed colors to the point that they could be identified with an analysis of the visible spectrum. Sodium chloride, for example, turned a shade of yellow similar to that visible in a geologically young area of Europa known as Tara Regio.

“Sodium chloride is a bit like invisible ink on Europa’s surface. Before irradiation, you can’t tell it’s there, but after irradiation, the color jumps right out at you,” says Hand, scientist at JPL and co-author of the Science Advances paper.

“No one has taken visible wavelength spectra of Europa before that had this sort of spatial and spectral resolution. The Galileo spacecraft didn’t have a visible spectrometer. It just had a near-infrared spectrometer,” says Caltech graduate student Samantha Trumbo, the lead author of the paper.

“People have traditionally assumed that all of the interesting spectroscopy is in the infrared on planetary surfaces, because that’s where most of the molecules that scientists are looking for have their fundamental features,” Brown says.

By taking a close look with the Hubble Space Telescope, Brown and Trumbo were able to identify a distinct absorption in the visible spectrum at 450 nanometers, which matched the irradiated salt precisely, confirming that the yellow color of Tara Regio reflected the presence of irradiated sodium chloride on the surface.

“We’ve had the capacity to do this analysis with the Hubble Space Telescope for the past 20 years,” Brown says. “It’s just that nobody thought to look.”

While the finding does not guarantee that this sodium chloride is derived from the subsurface ocean (this could, in fact, simply be evidence of different types of materials stratified in the moon’s icy shell), the study’s authors propose that it warrants a reevaluation of the geochemistry of Europa.

“Magnesium sulfate would simply have leached into the ocean from rocks on the ocean floor, but sodium chloride may indicate that the ocean floor is hydrothermally active,” Trumbo says. “That would mean Europa is a more geologically interesting planetary body than previously believed.”

The study is titled Sodium chloride on the surface of Europa.” This research was supported by the NASA Earth and Space Science Fellowship Program, the Space Telescope Science Institute, and JPL.

Materials provided by California Institute of Technology