New mirror-coating technology promises dramatic improvements in telescopes

UC Santa Cruz researchers worked with Structured Materials Industries to design and build an atomic layer deposition (ALD) system large enough to accommodate telescope mirrors. Andrew Phillips, Nobuhiko Kobayashi, and David Fryauf (l to r) examine the deposition chamber.

Materials scientist Nobuhiko Kobayashi wasn't quite sure why the astronomer he met at a wine-tasting several years ago was so interested in his research, but as he learned more about telescope mirrors it began to make sense.

"It turns out that improving the performance of mirrors is all about thin-film materials, and that's what I do. So then I got hooked," said Kobayashi, a professor of electrical engineering in the Baskin School of Engineering at UC Santa Cruz.

The astronomer was Joseph Miller, former director of UC Observatories (UCO), whose interest led to a thriving collaboration between Kobayashi and UC Santa Cruz astronomers Andrew Phillips and Michael Bolte. With funding from the National Science Foundation and support from current UCO director Claire Max, the researchers are developing new protective coatings for large silver-based telescope mirrors by adapting a technique widely used in the microelectronics industry.

According to Phillips, most astronomical telescope mirrors use aluminum for the reflective layer, despite the superior reflective properties of silver. "Silver is the most reflective material, but it is finicky to work with, and it tarnishes and corrodes easily," he said. "You need barrier layers on top that can keep anything from getting through to the silver without messing up the optical characteristics of the mirror."

Existing telescopes could substantially increase their efficiency by recoating their mirrors with silver instead of aluminum. "It is by far the cheapest way to make our telescopes effectively bigger," said Bolte. "The reason we want bigger telescopes is to collect more light, so if your mirrors reflect more light it's like making them bigger."

The new coating technology being developed at UC Santa Cruz could make that feasible. The researchers are using a technique called atomic layer deposition (ALD), which gradually builds a thin film of material, one molecular layer at a time, with excellent uniformity, thickness control, and conformity to the surface of the substrate. In a pilot study, ALD provided much better protective coatings for silver mirror samples than traditional physical deposition techniques.

"Atomic layer deposition performs significantly better," Phillips said. "The problem is that the systems used in the electronics industry are designed for silicon wafers, so they're too small for a telescope mirror."

The results of the pilot study, which used an ALD system in Kobayashi's lab designed for microelectronics, convinced the team to design a larger system that could accommodate telescope mirrors. They filed for a patent on their concept and found an equipment vendor willing to work with them to build the system. The vendor, Structured Materials Industries (SMI) in Piscataway, New Jersey, makes thin-film deposition systems for the microelectronics industry.

"We gave them the concept and our requirements, and they did the engineering design work and fabrication," Kobayashi said.

The new system was delivered to his laboratory in July and has performed well in initial testing. The researchers will use the system to demonstrate that it works for telescope mirrors and other large substrates and to continue perfecting the coatings. The system can accommodate a mirror up to 0.9 meter in diameter, and there is no reason the design could not be scaled up to accommodate even larger mirrors or mirror segments, Phillips said. The 10-meter primary mirrors of the twin Keck Telescopes in Hawaii are composed of hexagonal segments 1.8 meters across, and the mirror segments for the Thirty Meter Telescope (TMT) will be 1.4 meters across.

According to Bolte, the desire to use silver on the TMT mirror segments is a major driver of their research on new coating technologies. But he expects the technology will also be used to recoat the mirrors of existing telescopes. An aluminum-coated mirror lasts about three to five years before it needs recoating, a process that puts the telescope temporarily out of action.

"We hate to lose telescope time, and we lose a lot of nights recoating segments at Keck," Phillips said. "We'd like to have a silver coating that could last five to ten years."

At this point, the researchers are using a physical deposition process to put the silver coating on the mirror blanks along with an initial barrier layer to protect the silver while the mirror is transferred to the ALD system. Atomic layer deposition is then used for the final barrier layers.

"Right now, it's a hybrid process, but we're following the development of atomic layer deposition for the silver coating as well," Phillips said.

Read more at Science Daily

Mercury's poles may be icier than scientists thought

Brown University researchers have found new evidence of ice sheets in permanently shadowed craters near the north pole of Mercury. The researcher also suggests that smaller-scale deposits may exist between craters, which would vastly increase the surface ice inventory in Mercury.

The scorching hot surface of Mercury seems like an unlikely place to find ice, but research over the past three decades has suggested that water is frozen on the first rock from the sun, hidden away on crater floors that are permanently shadowed from the sun's blistering rays. Now, a new study led by Brown University researchers suggests that there could be much more ice on Mercury's surface than previously thought.

The study, published in Geophysical Research Letters, adds three new members to the list of craters near Mercury's north pole that appear to harbor large surface ice deposits. But in addition to those large deposits, the research also shows evidence that smaller-scale deposits scattered around Mercury's north pole, both inside craters and in shadowed terrain between craters. Those deposits may be small, but they could add up to a lot more previously unaccounted-for ice.

"The assumption has been that surface ice on Mercury exists predominantly in large craters, but we show evidence for these smaller-scale deposits as well," said Ariel Deutsch, the study's lead author and a Ph.D. candidate at Brown. "Adding these small-scale deposits to the large deposits within craters adds significantly to the surface ice inventory on Mercury."

The idea that Mercury might have frozen water emerged in the 1990s, when Earth-based radar telescopes detected highly reflective regions inside several craters near Mercury's poles. The planet's axis doesn't have much tilt, so its poles get little direct sunlight, and the floors of some craters get no direct sunlight at all. Without an atmosphere to hold in any heat from surrounding surfaces, temperatures in those eternal shadows have been calculated to be low enough for water ice to be stable. That raised the possibility these "radar-bright" regions could be ice.

That idea got a boost after NASA's MESSENGER probe entered Mercury's orbit in 2011. The spacecraft detected neutron signals from the planet's north pole that were consistent with water ice.

For this new study, Deutsch worked with Gregory Neumann from NASA's Goddard Space Flight Center to take a deep dive into the data returned from MESSENGER. They looked specifically at readings from the spacecraft's laser altimeter. The device is mostly used to map elevation, but it can also be used to track surface reflectance.

Neumann, an instrument specialist for the MESSENGER mission, helped to calibrate the altimeter's reflectance signal, which can vary depending upon whether the measurement is taken from directly overhead or at an oblique angle (known as "off-nadir"). That calibration enabled the researchers to detect high reflectance deposits consistent with surface ice in three large craters for which only off-nadir detections were available.

The addition of those craters to Mercury's ice inventory is significant. Deutsch estimates the total area of the three sheets to be about 3,400 square kilometers -- slightly larger than the state of Rhode Island.

But another major aspect of the work is that the researchers also looked at reflectance data for the terrain surrounding those three large craters. That terrain isn't as bright as the ice sheets inside the craters, but it's significantly brighter than the average Mercury surface.

"We suggest that this enhanced reflectance signature is driven by small-scale patches of ice that are spread throughout this terrain," Deutsch said. "Most of these patches are too small to resolve individually with the altimeter instrument, but collectively they contribute to the overall enhanced reflectance."

To seek further evidence that such smaller-scale deposits exist, the researchers looked though the altimeter data in search of patches that were smaller than the big crater-based deposits, but still large enough to resolve with the altimeter. They found four, each with diameters of less than about 5 kilometers.

"These four were just the ones we could resolve with the MESSENGER instruments," Deutsch said. "We think there are probably many, many more of these, ranging in sizes from a kilometer down to a few centimeters."

Knowing that these small-scale deposits exist, and that they're likely the source of the slightly brighter surface outside craters, could dramatically increase the ice inventory on Mercury. Similar small-scale ice deposits are thought to exist on the poles of the Moon. Research models have suggested that accounting for these small-scale deposits roughly doubles the amount of lunar real estate that could harbor ice. The same could be true on Mercury, the researchers say.

How this polar ice may have found its way to Mercury in the first place remains an open question, Deutsch says. The leading hypothesis is that it was delivered by water-rich comet or asteroid impacts. Another idea is that hydrogen may have been implanted in the surface by solar wind, later combining with an oxygen source to form water.

Jim Head, Deutsch's Ph.D. advisor and co-author of the research, said the work adds a new perspective on a critical question in planetary science.

Read more at Science Dialy

US Teens Are Growing Up More Slowly Than They Used To

A group of teenage boys.

Jean Twenge has been researching generational differences for 25 years. Of late, she started to notice that today’s teens aren’t dating and holding down jobs as much as they used to in past decades.

She’s not alone in making such observations, which have sparked spirited online debates about their implications.

“I’d seen trend pieces characterizing these trends as meaning teens were more ‘virtuous,’ when talking about declines in sex or alcohol, or that teens were ‘lazy’ when talking about declines in working,” Twenge, a professor of psychology at San Diego State University, told Seeker. “But I thought both of those missed the big picture — that teens were taking longer to grow up.”

She and her colleague Heejung Park, an assistant professor of psychology at Bryn Mawr College, decided to investigate the matter further.

They analyzed seven surveys, conducted between 1976 and 2016, of 8.3 million 13- to 19-year-olds. The surveys were nationally representative, reflecting the population of US teens in terms of gender, race/ethnicity, socioeconomic status, and geographic region.

In the surveys, teens were asked how they used their time, including their engagement in one or more activities that were considered to be adult in nature. These included dating, working for pay, going out without their parents, driving, and having sex. The massive amount of data allowed Twenge and Park to compare teens in the 2010s to teens in the 2000s, 1990s, 1980s, and 1970s.

The study, published in the journal Child Development, found that adolescents in the present decade are less likely to engage in such adult behaviors, which are mostly tied to independence from parental figures. The trend appeared across all demographic groups, and supports Twenge’s speculation that teens are growing up more slowly than their counterparts from previous decades did.

“I would not describe youths as ‘more immature,’” she said. “That doesn’t fit the larger pattern of the data. Is it more or less mature to have sex or drink alcohol in high school? It’s neither.”

Delayed development throughout the animal kingdom is usually associated with greater time for education, with humans gaining much of this in school. Less schooling does not necessarily mean less learning overall, however.

“For example, when young people on average had less educational opportunities and started working at a job or started their family at earlier ages, they were engaging in different types of learning,” Park explained. “As another example, in cultures and communities where formal schooling is less available, much learning takes place in the home setting through observations and interactions, rather than through explicit forms of teaching and communication.”

Twenge, who is the author of the book iGen: Why Today’s Super-Connected Kids Are Growing Up Less Rebellious, More Tolerant, Less Happy — and Completely Unprepared for Adulthood, noted that more people go to college now than they did in past years.

“Whether they are actually learning more is a question we can’t answer with this data,” she noted.

Three teenage girls taking a selfie.

The researchers determined that the trend toward teens engaging in fewer adult behaviors cannot be explained by the time youths generally spent on homework or extracurricular activities. Twenge and Park said that this is because time doing those activities decreased among eighth and tenth graders, but was steady among twelfth graders and college students.

The decline in adult activities among teens may be linked to the time they spend online, however, since this increased markedly over the span of the surveys.

Electronic devices such as computers and smartphones “likely accelerated some of the trends in the last 10 years, as many of them involve getting out of the house, which is now less necessary for communicating with friends,” explained Twenge.

Human physical development is on a different, genetics-driven timetable than these more culturally-driven changes. Other studies even show that some youths are going through puberty earlier now than they did in past decades. This can put the bodies of adolescents and teens in conflict with societal norms.

For example, while teens may be physically able to have children of their own, others may believe that such younger individuals are not emotionally and/or financially stable enough to have offspring. These same reasons, plus health concerns, have led to the passage of laws governing other adult-associated behaviors, such as driving.

“Due to the slow life strategy,” Twenge said, “adults believe teens should grow up more slowly, and then laws are passed to restrict their access to alcohol, cigarettes, etc.”

For the study, she and Park also examined how changes in family size, life expectancy, education, and the economy may have influenced the rate at which teens engage in adult activities.

These activities were less common during time periods when families had fewer children and higher median income, and when fewer people died of communicable diseases. Longer lives on average, women giving birth at later ages, and completion of education later in life were additional factors associated with teens growing up more slowly.

“Life history theory explicitly notes that slow or fast strategies are not inherently good or bad,” Twenge noted. “They are adaptations to the cultural context.”

“Young people today are exposed to different types of learning than prior generations, due to cultural changes and humans’ tendency to adapt to the changing environmental conditions,” Park added. “Each cultural environment has strengths and weaknesses, so it is important to recognize both what’s being gained and lost as our cultures change.”

Read more at Seeker

‘Astronauts' Simulating Mars Surface Mission Emerge After 8 Months of Isolation

HI-SEAS V crewmembers Brian Ramos and Laura Lark walk around the mock Mars habitat.

After spending eight months simulating life on Mars on the slopes of the Mauna Loa volcano, six "astronauts" emerged from their Hawaiian habitat on Sunday (Sept. 17) to return to civilization.

This concluded the fifth mock Mars mission of the NASA-funded HI-SEAS program (Hawaii Space Exploration Analog and Simulation). Operated by the University of Hawaii, this research project studies how groups of interplanetary travelers would work together on long-term missions while in cramped quarters.

During the mission, four men and two women lived in isolation from the rest of planet Earth and could eat only shelf-stable foods and occasional lab-grown vegetables. When communicating with the outside world, they had to deal with the 20-minute delay that astronauts on Mars would experience as well. And any time they went outside, they had to put on their spacesuits.

The Mission V crew entered the HI-SEAS dome on Jan. 19. During their eight-month stay on Mauna Loa, the world's largest active volcano, they conducted scientific experiments, performed daily exercises and maintained equipment in and around the dome. Outside the dome, the astronauts did geological fieldwork in their spacesuits just as if they were on Mars.

While HI-SEAS studies the more technical and practical aspects of living on Mars, a large part of the investigation is to see how a group of people live together in isolation with little to no privacy.

"Long-term space travel is absolutely possible," Laura Lark, IT specialist for HI-SEAS V, said in a video. "There are certainly technical challenges to be overcome. There are certainly human factors to be figured out, that’s part of what HI-SEAS is for. But I think that overcoming those challenges is just a matter of effort. We are absolutely capable of it."

After the crew emerged from the HI-SEAS dome at 9 a.m. EDT (1300 GMT), they " felt the sun and wind on their faces and ate fresh tropical papaya, pineapple and bananas with friends and family," University of Hawaii officials said in a statement.

"My advice to mission six is say, 'Yes.’" HI-SEAS V health and performance officer Brian Ramos said in the video. "If you have an opportunity whether it’s filming or learning a new science skill or flying the drone, going out to a lava tube, whatever it is, say, "Yes.' Take leadership on things. Honestly, you can come out of here in eight months learning a ton of stuff."

Read more at Seeker

Dogs' social skills linked to oxytocin sensitivity

A golden retriever turns to his owner for affection.

The tendency of dogs to seek contact with their owners is associated with genetic variations in sensitivity for the hormone oxytocin, according to a new study from Linköping University, Sweden. The results have been published in the scientific journal Hormones and Behavior and contribute to our knowledge of how dogs have changed during their development from wolf to household pet.

During their domestication from their wild ancestor the wolf to the pets we have today, dogs have developed a unique ability to work together with humans. One aspect of this is their willingness to "ask for help" when faced with a problem that seems to be too difficult. There are, however, large differences between breeds, and between dogs of the same breed. A research group in Linköping, led by Professor Per Jensen, has discovered a possible explanation of why dogs differ in their willingness to collaborate with humans.

The researchers suspected that the hormone oxytocin was involved. It is well-known that oxytocin plays a role in social relationships between individuals, in both humans and animals. The effect of oxytocin depends on the function of the structure that it binds to, the receptor, in the cell. Previous studies have suggested, among other things, that differences in dogs' ability to communicate are associated with variations in the genetic material located close to the gene that codes for the oxytocin receptor. The researchers in the present study examined 60 golden retrievers as they attempted to solve an insoluble problem.

"The first step was to teach the dogs to open a lid, and in this way get hold of a treat. After this, they were given the same task with the lid firmly fixed in place, and thus impossible to open. We timed the dogs to see how long they attempted on their own, before turning to their owner and asking for help," says Mia Persson, PhD student at the Department of Physics, Chemistry and Biology, and principal author of the article.

Before the behavioural test, the researchers increased the levels of oxytocin in the dogs' blood by spraying the hormone into their nose. As a control, the dogs carried out the same test after having received a spray of neutral salt water in the same way. The researchers also collected DNA using a cotton swab inside the dogs' cheek, and determined which variant of the gene for the oxytocin receptor that each dog had.

The results showed that dogs with a particular genetic variant of the receptor reacted more strongly to the oxytocin spray than other dogs. The tendency to approach their owner for help increased when they received oxytocin in their nose, compared with when they received the neutral salt water solution. The researchers suggest that these results help us understand how dogs have changed during the process of domestication. They analysed DNA also from 21 wolves, and found the same genetic variation among them. This suggests that the genetic variation was already present when domestication of the dogs started, 15,000 years ago.

"The results lead us to surmise that people selected for domestication wolves with a particularly well-developed ability to collaborate, and then bred subsequent generations from these," says Mia Persson.

The genetic variations that the researchers have studied do not affect the oxytocin receptor itself: they are markers used for practical reasons. Further research is necessary to determine in more detail which differences in the genetic material lie behind the effects.

Per Jensen points out that the study shows how social behaviour is to a large extent controlled by the same genetic factors in different species.

Read more at Science Daily

New evidence for small, short-lived drops of early universe quark-gluon plasma?

The PHENIX detector at the Relativistic Heavy Ion Collider (RHIC) with a superimposed image of reconstructed particle tracks picked up by the detector.

Particles emerging from even the lowest energy collisions of small deuterons with large heavy nuclei at the Relativistic Heavy Ion Collider (RHIC) -- a U.S. Department of Energy Office of Science User Facility for nuclear physics research at DOE's Brookhaven National Laboratory -- exhibit behavior scientists associate with the formation of a soup of quarks and gluons, the fundamental building blocks of nearly all visible matter. These results from RHIC's PHENIX experiment suggest that these small-scale collisions might be producing tiny, short-lived specks of matter that mimics what the early universe was like nearly 14 billion years ago, just after the Big Bang.

Scientists built RHIC, in large part, to create this "quark-gluon plasma" (QGP) so they could study its properties and learn how Nature's strongest force brings quarks and gluons together to form the protons, neutrons, and atoms that make up the visible universe today. But they initially expected to see signs of QGP only in highly energetic collisions of two heavy ions such as gold. The new findings -- correlations in the way particles emerge from the collisions that are consistent with what physicists have observed in the more energetic large-ion collisions -- add to a growing body of evidence from RHIC and Europe's Large Hadron Collider (LHC) that QGP may be created in smaller systems as well.

The PHENIX collaboration has submitted the findings in two separate papers to the journals Physical Review Letters and Physical Review C, and will present these results at a meeting in Krakow, Poland this week.

"These are the first papers that come out of the 2016 deuteron-gold collisions, and this is one indication that we are probably creating QGP in small systems," said Julia Velkovska, a deputy spokesperson for PHENIX from Vanderbilt University. "But there are other things that we have seen in the larger systems that we have yet to investigate in this new data. We'll be looking for other evidence of QGP in the small systems using different ways to study the properties of the system we are creating," she said.

Collective flow

One of the earliest signs that RHIC's collisions of two gold ions were creating QGP came in the form of "collective flow" of particles. More particles emerged from the "equator" of two semi-overlapping colliding ions than perpendicular to the collision direction. This elliptical flow pattern, scientists believe, is caused by interactions of the particles with the nearly "perfect" -- meaning free-flowing -- liquid-like QGP created in the collisions. Since then, collisions of smaller particles with heavy ions have resulted in similar flow patterns at both RHIC and the LHC, albeit on a smaller scale. There has also been evidence that flow patterns have a strong relationship with the geometrical shape of the projectile particle that is colliding with the larger nucleus.

"With these results in hand, we wanted to try smaller and smaller systems at different energies," Velkovska said. "If you change the energy, you can change the time that the system stays in the liquid phase, and maybe make it disappear."

In other words, they wanted to see if they could turn the creation of QGP off.

"After so many years we have learned that when QGP is created in the collisions we know how to recognize it, but that doesn't mean we really understand how it works," Velkovska said. "We are trying to understand how the perfect-fluid behavior emerges and evolves. What we are doing now -- going down in energy, changing the size -- is an effort to learn how this behavior arises in different conditions. RHIC is the only collider in the world that allows such a range of studies over different collision energies with different colliding particle species."

Turing down the energy

Over a period of about five weeks in 2016, the PHENIX team explored collisions of deuterons (made of one proton and one neutron) with gold ions at four different energies (200, 62.4, 39, and 19.6 billion electron volts, or GeV).

"Thanks to the versatility of RHIC and the ability of the staff in Brookhaven's Collider-Accelerator Department to quickly switch and tune the machine for different collision energies, PHENIX was able to record more than 1.5 billion collisions in this short period of time," Velkovska said.

For the paper submitted to PRC, Darren McGlinchey, a PHENIX collaborator from Los Alamos National Laboratory, led an analysis of how particles emerged along the elliptical plane of the collisions as a function of their momentum, how central (fully overlapping) the collisions were, and how many particles were produced.

"Using a deuteron projectile produces a highly elliptical shape, and we observed a persistence of that initial geometry in the particles we detect, even at low energy," McGlinchey said. Such shape persistence could be caused by interaction with a QGP created in these collisions. "This result is not sufficient evidence to declare that QGP exists, but it is a piece of mounting evidence for it," he said.

Ron Belmont, a PHENIX collaborator from the University of Colorado, led an analysis of how the flow patterns of multiple particles (two and four particles at each energy and six at the highest energy) were correlated. Those results were submitted to PRL.

"We found a very similar pattern in both two- and four-particle correlations for all the different energies, and in six-particle correlations at the highest energy as well," Belmont said.

"Both results are consistent that particle flow is observed down to lowest energy. So the two papers work together to paint a nice picture," he added.

There are other possible explanations for the findings, including the postulated existence of another form of matter known as color glass condensate that is thought to be dominated by the presence of gluons within the heart of all visible matter.

"To distinguish color glass condensate from QGP, we need more detailed theoretical descriptions of what these things look like," Belmont said.

Read more at Science Daily

Changes in Earth's crust caused oxygen to fill the atmosphere

Matthijs Smit of the University of British Columbia examines ancient rocks from the deep crust in Norway during the summer of 2017.

Scientists have long wondered how Earth's atmosphere filled with oxygen. UBC geologist Matthijs Smit and research partner Klaus Mezger may have found the answer in continental rocks that are billions of years old.

"Oxygenation was waiting to happen," said Smit. "All it may have needed was for the continents to mature."

Earth's early atmosphere and oceans were devoid of free oxygen, even though tiny cyanobacteria were producing the gas as a byproduct of photosynthesis. Free oxygen is oxygen that isn't combined with other elements such as carbon or nitrogen, and aerobic organisms need it to live. A change occurred about three billion years ago, when small regions containing free oxygen began to appear in the oceans. Then, about 2.4 billion years ago, oxygen in the atmosphere suddenly increased by about 10,000 times in just 200 million years. This period, known as the Great Oxidation Event, changed chemical reactions on the surface of the Earth completely.

Smit, a professor in UBC's department of earth, ocean & atmospheric sciences, and colleague, professor Klaus Mezger of the University of Bern, were aware that the composition of continents also changed during this period. They set out to find a link, looking closely at records detailing the geochemistry of shales and igneous rock types from around the world -- more than 48,000 rocks dating back billions of years.

"It turned out that a staggering change occurred in the composition of continents at the same time free oxygen was starting to accumulate in the oceans," Smit said.

Before oxygenation, continents were composed of rocks rich in magnesium and low in silica -- similar to what can be found today in places like Iceland and the Faroe Islands. But more importantly, those rocks contained a mineral called olivine. When olivine comes into contact with water, it initiates chemical reactions that consume oxygen and lock it up. That is likely what happened to the oxygen produced by cyanobacteria early in Earth's history.

However, as the continental crust evolved to a composition more like today's, olivine virtually disappeared. Without that mineral to react with water and consume oxygen, the gas was finally allowed to accumulate. Oceans eventually became saturated, and oxygen crossed into the atmosphere.

"It really appears to have been the starting point for life diversification as we know it," Smit said. "After that change, the Earth became much more habitable and suitable for the evolution of complex life, but that needed some trigger mechanism, and that's what we may have found."

As for what caused the composition of continents to change, that is the subject of ongoing study. Smit notes that modern plate tectonics began at around the same time, and many scientists theorize that there is a connection.

Read more at Science Daily

Ancient Greeks May Have Deliberately Built Sacred Sites on Earthquake Faults

Temple of Apollo ruins in Delphi, Greece

Archeologists and other scientists have long known that intoxicating gases emanating from water flowing from deep within the earth likely produced the visions of the oracle of Delphi, a seer who guided ancient Greeks with her prophecies from around 800 BC through the 4th century AD from her temple on Mount Parnassus.

Now new research suggests many other Greek sacred sites were built on similar fissures created by earthquakes throughout the Eastern Mediterranean.

“The ancient Greeks placed great value on hot springs unlocked by earthquakes,” said Iain Stewart, professor of geoscience communication and director of the Sustainable Earth Institute at the University of Plymouth in Britain. “But perhaps the building of temples and cities close to these sites was more systematic than has previously been thought.”

In a study published recently in the Proceedings of the Geologists’ Association, Stewart showed how temples and other structures at Mycenae, Ephesus, Cnidus, and Hierapolis were, like Delphi, built and rebuilt over earthquake faults.

In Cnidus, an ancient, ruined city in what is now southwestern coastal Turkey, for example, locals erected a temple in the same place — over a fault in hindsight — even after earthquakes wrecked it.

“You think, ‘That’s bad luck, isn’t it?’” said Stewart, describing when he first reached his findings after reviewing his data. “Then it dawns on you. These people weren’t stupid. There was this grand dawning that there was probably something deliberate here.”

The pattern repeats in other cities, reflecting how Greeks viewed the underworld as the destination for the soul after death and a source of mystical power and knowledge. “We don’t have a culture that looks down,” said Stewart. “We have a culture that looks up to the stars.”

Conversely, in his paper Stewart speculates that seismic activity could have cut off hot springs that had justified an oracle at Perachora Heraion, a sanctuary founded in honor of the goddess Hera in the 9th century BC near Corinth but then fell into disuse in 300 BC potentially after earthquakes.

Greeks also of course didn’t live in cities with skyscrapers and millions of residents, either, he added. Earthquakes would have been viewed more as mystical occurrences and not natural disasters caused by the movement of tectonic plates. Historical and geological records show that earthquakes were frequent at the height of ancient Greek civilization, he added.

“It’s hard [for people today] to separate the modern take that earthquakes are dangerous,” said Stewart. “We kind of know too much. We know what they can do. In ancient times, they would have seen them very differently. In the course of 30 seconds, the ground would open up and then everything would go back to normal.”

Stewart added that archeologists might also look at sacred sites in South America, the Middle East, and Asia to see whether earthquake fault lines played a role in their construction.

Read more at Seeker

Measuring a crucial mineral in the mantle

Olivine, the most abundant mineral found in the Earth's mantle, is considered to be a robust model of the interior of the Earth's composition.

University of Delaware professor Jessica Warren and colleagues from Stanford University, Oxford University and University of Pennsylvania, reported new data that material size-effects matter in plate tectonics.

Plate tectonics, the way the Earth's plates move apart and come back together, has been used since the 1960s to explain the location of volcanoes and earthquakes.

The study (link here) published Wednesday, Sept. 13 in the American Association for the Advancement of Science journal Science Advances, resolves 40 years of disagreement in datasets about the strength of olivine, the most abundant mineral found in the upper 250 miles or so of the Earth, known as the mantle.

"Measuring the strength of olivine is critical to understanding how strong tectonic plates are, which, in turn, matters to how plates break and create subduction zones like those along the Cascadia plate, which runs down the west coast of Canada to the west coast of the United States," said Warren, a geologist in the College of Earth, Ocean, and Environment. It's also important for understanding how plates move around over the million-year time scales.

The paper demonstrated that olivine's strength is size-sensitive and that olivine is stronger the smaller the volume that is measured, something that has been known in materials science for many metals and ceramics, but has not been studied in a geological material before.

Warren explained that the problem with studying rocks on the earth's surface is that they are no longer subjected to the high pressures found inside the earth that cause materials to flow (like ice in a glacier). Recreating these elevated pressures in the laboratory is difficult, making it hard for scientists to study material strength in the lab.

The researchers used a technique, called instrumented nanoindentation, to measure olivine's strength. The technique allowed them to recreate pressure conditions similar to those inside the earth by pressing a diamond tip that was carefully machined to a specific geometry into the olivine crystal to measure the material's response. The diamond tips ranged in size from 5 to 20 microns (0.000001 meter). The researchers performed hundreds of indentation tests on tiny olivine crystals less than a centimeter square and found that the olivine crystal became weaker as the size of the diamond tip increased.

To validate this size-effect, the researchers reviewed the available literature data on the strength of olivine to determine the sizes and areas that had been tested in previous experiments dating to the late 1970s. The size-effect showed up in the old data, too.

"The reason 40 years' worth of data don't agree from one experiment to the next is because scientists were measuring different sizes or areas of olivine," Warren said. "But if you plot the same information as a function of the sample size, the datasets, in fact agree, and display the same general trend -- the larger the indentation in the material tested, the weaker the olivine becomes."

Now that Warren and her colleagues understand this size-effect, they are turning their attention to how temperature affects the strength of olivine, and more broadly, on where tectonic plates might break and give rise to potential subduction zones.

Temperatures inside the earth are much hotter than on the surface and can range from 1,470 to 2,200 degrees Fahrenheit (800 to 1,200 degrees Celsius).

The team also will consider what role water plays in the structure of olivine minerals and rocks in the earth. According to Warren, current estimates suggest the earth contains the equivalent of 50 percent to 4 times the amount of water found in the global ocean.

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Light on exoplanets may be quite different from Earth: Different photosynthesis?

Artists impressions of a habitable planet around M-dwarfs (left) and primordial Earth (right). The surface of M-dwarf planet is illuminated by visible light. On the other hand, similar light conditions are expected underwater, since only blue-green light can penetrate meters of water.

Researchers at the Astrobiology Center (ABC) of National Institutes of Natural Science (NINS) in Japan and their colleagues have proposed a prediction that red-edge could be observed as on the Earth even on exoplanets around M-dwarfs. They pointed out that the first oxgenic photorophs are most likely to have evolved underwater to utilize visible light just like what had happened in the primordial ocean on the Earth. They examined light adaptation mechanisms of visible- and IR-radiation-using phototrophs required for adapting to land habitats and found out that IR-using phototrophs struggle to adapt to changing light condition at the boundary of water and land surface.

M-dwarfs or red dwarfs are small (0.5-0.1 solar-masses) and cool ( ~3000 Kelvin) stars, and are abundant in universe. The Sun-like stars have been attracting most attention as a plausible target for searching habitable exoplanets. However, nearby M-dwarfs are becoming the most extensive targets for habitable planet searches because they are the most abundant nearby stars and thus could be the first candidate for detecting any biosignatures on exoplanets via transit or direct imaging observations in near future.

One of the most important exoplanetary biosignatures is a specific reflection pattern on the land surface named 'red-edge', which is caused by vegetation such as forests and grasslands. On the Earth, red-edge appears between red and infrared (IR) wavelengths, since red-light is absorbed for photosynthesis while IR radiation is reflected. In previous studies, it was predicted that red-edge position on exoplanets should be decided by the radiation spectrum by nearby stars. Around M-dwarfs, red-edge was expected to be shifted to a longer wavelength, since planets on the exoplanets use abundant IR radiation for photosynthesis.

Researchers at the Astrobiology Center (ABC) of National Institutes of Natural Science (NINS) in Japan and their colleagues have proposed and alternative prediction that red-edge could be observed as on the Earth even on exoplanets around M-dwarfs in the online journal Scientific Reports on August 8th, 2017. They pointed out that the first oxgenic photorophs are most likely to have evolved underwater to utilize visible light just like what had happened in the primordial ocean on the Earth. They examined light adaptation mechanisms of visible- and IR-radiation-using phototrophs required for adapting to land habitats and found out that IR-using phototrophs struggle to adapt to changing light condition at the boundary of water and land surface. Kenji Takizawa, read author of the study, said "It is too risky to utilize IR-radiation during water-to-land evolution."

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