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601

EEE / Rock hounds are on the hunt for new carbon minerals

« on: November 20, 2016, 06:09:28 PM »

Like many abandoned mines, the Eureka uranium mine in northern Spain is a maze of long, dank tunnels. Water seeping down the walls carries dissolved substances that percolated through rocks overhead. As the water evaporates into the tunnels’ cool air, some of those dissolved ingredients combine to make new substances in solid form.

“The mine is a crystallization factory of weird minerals,” says Jordi Ibáñez-Insa, a physicist at the Institute of Earth Sciences Jaume Almera in Barcelona.

Including the uranium-bearing ores that attracted miners to Eureka in the first place, scientists visiting the mine have cataloged 61 different minerals — solids that have a distinct chemical recipe and arrangement of atoms. The latest find, called abellaite, is a rarity that grows in small pincushions of tiny crystalline needles about 40 to 50 micrometers long. Discovered in July 2010, the mineral has been found only on the walls of a 3-meter-long stretch of one tunnel, says Ibáñez-Insa.

Abellaite is uncommon in another sense: It contains carbon. Of the 5,161 minerals characterized by scientists and recognized by the International Mineralogical Association, just 8 percent, or 416, include carbon.

The Carbon Mineral Challenge, launched last December and running until September 2019, exhorts researchers to scour the landscape — and their museum drawers — for unknown carbon-bearing minerals. In a recent analysis, scientists estimate that there are at least 548 carbon minerals on Earth. That means well over 100 are waiting to be noticed.

602

EEE / Saturn’s moon Dione might harbor an underground ocean

« on: November 20, 2016, 06:08:23 PM »

A satellite of Saturn joins the club of moons with possible oceans. A subsurface sea of water might hide beneath the icy crust of Dione, one of Saturn’s moons, researchers report online October 9 in Geophysical Research Letters. That puts Dione in good company alongside Enceladus (another moon of Saturn) and several moons of Jupiter, as well as possibly Pluto (SN Online: 9/23/16).

Dione’s ocean is about 100 kilometers below the surface and roughly 65 kilometers deep, Mikael Beuthe, a planetary scientist at the Royal Observatory of Belgium in Brussels, and colleagues report. They inferred the ocean’s presence from measurements of Dione’s gravity made by the Cassini spacecraft.

603

EEE / Comet 67P cracking under pressure

« on: November 20, 2016, 06:07:50 PM »

PASADENA, Calif. — It’s hard being a comet sometimes. Comet 67P/Churyumov-Gerasimenko is developing stress fractures and might break apart in the next several hundred years.

Comet 67P is famous for its oddball shape. With two lobes joined together at a neck, it vaguely resembles an interplanetary peanut. The Rosetta spacecraft, which ended its 26-month visit to the comet in September (SN Online: 9/29/16), noticed a large crack in the neck in 2014. After the comet made its closest approach to the sun in August 2015, the fissure grew by several hundred meters and new cracks appeared.

The fractures appear to be developing as forces subtly bend the comet to and fro, Stubbe Hviid, a planetary scientist at the German Aerospace Center Institute of Planetary Research in Berlin, reported October 17 in a press conference at a meeting of the American Astronomical Society’s Division for Planetary Sciences. Hviid and colleagues combined maps from Rosetta with computer simulations of all the forces at work within the comet to determine how the cracks develop. They found that the two bulbous ends rock in opposite directions as the comet spins, flexing the neck and creating severe stress. Because the comet isn’t held together strongly — it’s a conglomeration of dust and ice not much stickier than snow, Hviid said — the neck is starting to break. After a few hundred more years, he said, the comet could fold itself in half as the two lobes snap apart and smoosh together.

604

EEE / Lava may be flowing from Venus volcano

« on: November 20, 2016, 06:07:02 PM »

PASADENA, Calif. — Venus is already known to host a hellish landscape with stifling temperature and suffocating pressure — and, a new study now hints, possibly rivers of lava oozing out of a volcano.

Several lava flows appear to be recently or currently active on a Venusian volcano known as Idunn Mons, planetary scientist Piero D’Incecco reported October 17 at a meeting of the American Astronomical Society’s Division for Planetary Sciences. Hot spots first detected by the Venus Express spacecraft, which orbited the planet from 2006 to 2015, had already hinted that the volcano might be active. But Venus guards its secrets tightly. Orbiters have trouble peering through the thick clouds that blanket the planet, and landers don’t last long because of the extreme environment.

Venus Express couldn’t see the source of the heat, so the researchers combined its data with maps from the Magellan spacecraft, which orbited from 1990 to 1994, and computer simulations to figure out how Idunn Mons could create the hot spots. D’Incecco, of the German Aerospace Center Institute of Planetary Research in Berlin, and colleagues deduced that five lava flows — one on top of the mountain and four running down the flanks — are responsible.

Researchers have long suspected that Venus is volcanically active, but don’t have any direct evidence yet (SN Online: 6/19/15). Testing whether Idunn Mons, or anywhere else, is belching lava will have to wait for future spacecraft. Both NASA and the European Space Agency are currently considering proposals for several Venus orbiters that could visit sometime in the next decade.   

605

EEE / Possibly cloudy forecast for parts of Pluto

« on: November 20, 2016, 06:06:26 PM »

The forecast on Pluto is clear with less than a 1 percent chance of clouds. Images from the New Horizons spacecraft show hints of what could be a few isolated clouds scattered around the dwarf planet, the first seen in otherwise clear skies.

Seven cloud candidates appear to hug the ground in images taken shortly after the probe buzzed by the planet in July 2015. Along the line where day turns to night, several isolated bright patches appear. These are consistent with clouds forming at sunset and sunrise, said mission head Alan Stern during an October 18 news conference at a meeting of the American Astronomical Society’s Division for Planetary Sciences.

If they are clouds, they’re probably made of ethane, acetylene or hydrogen cyanide, based on what researchers have learned about Pluto’s atmosphere — though they might not be clouds, just reflective splotches on the surface, Stern said.  Without stereo imaging, it’s impossible to tell how high off the ground the patches are, or whether they’re in the sky at all. Since New Horizons isn’t returning to Pluto — it’s hurtling deep into the Kuiper belt — the spacecraft won’t be able to take another look at the cloud candidates and answer these questions. That will have to wait until another spacecraft goes back to orbit Pluto, Stern said.

606

EEE / Experts don’t agree on age of Saturn’s rings

« on: November 20, 2016, 06:05:55 PM »

PASADENA, Calif. — Saturn’s rings have maintained a youthful look, while still possibly being almost as old as the solar system itself. The dazzling belts of ice continue to keep their age a secret, but researchers hope to get answers from a spacecraft orbiting the ringed planet.

Data from the Cassini spacecraft, in orbit since 2004, may help resolve a decades-long debate over the age of Saturn’s rings, wide belts of shiny ice chunks orbiting the planet. They may be primordial, dating back to roughly 4.6 billion years ago, or a recent addition in the last 100 million years or so. Evidence for both scenarios was presented October 16 at a meeting of the American Astronomical Society’s Division for Planetary Sciences.

There’s not enough pollution in the rings for them to have been around for a long time, argues planetary scientist Paul Estrada of the SETI Institute in Mountain View, Calif. Cassini data show that about 25 times as much debris — mostly from the Kuiper belt beyond Neptune — rains down on the rings than previously thought. All that interplanetary rain should not just darken the rings, but each impact should redistribute material as well. Sharp contrasts in composition seen at the inner edge of the main ring can’t have been sustained for more than a few hundred million years, Estrada says.

The trouble with making rings so recently is how to do it. “It’s hard to make rings in the last 100 million years,” says Larry Esposito, a planetary scientist at the University of Colorado Boulder. “This is not an exciting time.” Saturn’s rings were probably created after a moon or some passing icy body got torn apart in a collision or by wandering too close to the planet. But there hasn’t been much stuff flying around Saturn or the solar system in the last several billion years.

Esposito argues that despite some youthful appearances, the rings are ancient and recycle material lurking beneath their top layers, keeping the pollution levels lower than expected. Also, some lightweight rings could have formed quite recently and still look pristine, he says, while the most massive part of the rings endured for billions of years.

Part of the solution to the age question is knowing how massive the rings are. Observations from Cassini suggest that the rings are relatively hefty — possibly comparable to Saturn’s moon Mimas — though that’s not well known. “It’s a lot easier to make a massive ring if you make it early,” says Glen Stewart, also at Colorado Boulder. Billions of years ago more material was available to make a heavy ring than in recent times.

A lightweight ring could be formed more recently, however. Computer simulations suggest that the orbits of moons around Saturn could have changed a lot in the last several hundred million years or so, Estrada says. Those shifting orbits could lead to several different scenarios in which moons destroy one another, creating icy debris that spreads out and forms the rings.

In the coming year, this debate could be moot. Leading up to the end of Cassini’s mission in September, the spacecraft is going to start some daring maneuvers to try and measure how much mass is in the rings.  Cassini will dive between the planet and the rings several times, skimming Saturn’s atmosphere. “This is kamikaze stuff,” Stewart says. “For the first few orbits, they’re putting the antenna forward as an impact shield.”

By getting inside the rings, researchers can measure the gravitational tug on the spacecraft from the planet and compare that with earlier orbits where both the planet and the rings tugged on the probe. And more than scientific curiosity is on the line. “On the Cassini mission, there’s a betting pool about the mass of the rings,” Esposito says.

Figuring out the mass and age of Saturn’s rings isn’t just about solving one mystery about one aspect of one planet. Understanding how Saturn became bejeweled might offer insight into why other planets differ from one another, which in turn could reveal more details about their origins. “Why does Saturn have big rings but Jupiter doesn’t?” asks Esposito. “Is it just a matter of luck, or a matter of time?”

And rings aren’t unique to planets; they form around stars as well. Belts of ice and dust encircling young stars are thought to be where planets form throughout the universe. The disk that formed our solar system is long gone, says Esposito, but the physics underlying both that disk and the one around Saturn are largely the same. Understanding one can help researchers understand the other.

607

EEE / First peek under clouds reveals Jupiter’s surprising depths

« on: November 20, 2016, 06:05:13 PM »

PASADENA, Calif. — Jupiter’s clouds have deep roots. The multicolored bands that wrap around the planet reach hundreds of kilometers down into the atmosphere, NASA’s Juno spacecraft reveals, providing an unprecedented peek into the giant planet’s interior.

“Whatever’s making those colors and stripes still exists pretty far down,” planetary scientist Scott Bolton, head of the Juno mission, said October 19 at a meeting of the American Astronomical Society’s Division for Planetary Sciences. “That came as a surprise to many scientists.” Until now, researchers weren’t sure if Jupiter’s stripes were just blemishes atop the clouds or extended farther inward. The bands reach at least 350 to 400 kilometers beneath the cloud deck, Bolton reported in a news conference.

Juno arrived at Jupiter on July 4 and made its first up-close investigation of the planet on August 27 (SN: 10/1/16, p. 13). Coming within 5,000 kilometers of the cloud tops, Juno recorded the intensity of radio waves emanating from the planet. Different frequencies come from different depths; low frequencies originate from deep in the atmosphere while high frequencies originate higher up.

“Deep down, Jupiter is similar but also very different than what we see on the surface,” said Bolton, of the Southwest Research Institute in San Antonio. Some bands broaden while others vanish. “We can’t tell what all of it means yet, but it’s telling us hints about the deep dynamics and chemistry of Jupiter’s atmosphere.”

608

EEE / X-ray mystery shrouds Pluto

« on: November 20, 2016, 06:04:41 PM »

X-rays appear to be trickling away from Pluto, even though the dwarf planet has no obvious way of making the high-energy photons, a new study reports.

Given what researchers have learned about Pluto since the New Horizons spacecraft flew by in 2015 (SN: 8/8/15, p. 6), the discovery is surprising. For many planets and comets, X-rays are generated when the solar wind, a stream of charged particles from the sun, runs into neutral gas atoms or magnetic fields from these bodies. But the environment around Pluto isn’t conducive to producing X-rays: the dwarf planet has no measurable magnetic field, its atmosphere is very thin, and it’s losing that atmosphere at rates much lower than expected.

“We naively thought Pluto might be losing its atmosphere at the same rate as [some] comets,” says Carey Lisse, a planetary astronomer at the Applied Physics Laboratory in Laurel, Md. “We knew comets make X-rays, so we hoped that Pluto did, too.” Instead, interactions between the solar wind and a tenuous tail of methane gas hundreds of times longer than Pluto’s diameter might be the culprit, Lisse and colleagues suggest online October 25 on arXiv.org.

Lisse’s team used the Chandra X-ray telescope, once in 2014 and three more times in 2015, to look for Pluto X-rays. Chandra detected just seven photons streaming from Pluto in a total of about two days’ worth of observing time. Though the signal isn’t strong, that’s about six or seven more photons than expected based on New Horizons’ measurements of Pluto’s atmosphere and the solar wind.

“It’s a very puzzling finding,” says Konrad Dennerl, an astrophysicist at the Max Planck Institute for Extraterrestrial Physics in Garching, Germany. “I’m not fully convinced,” he adds. “It’s a very low signal.”

Lisse and collaborators note that the signal appears to follow Pluto across the sky. They detected X-ray photons on four separate occasions. The energy of the photons doesn’t appear to match that of the spurious X-ray noise that peppers the telescope, so the signal appears genuine. Still, Lisse and Dennerl are teaming up to get some Pluto time with another X-ray observatory, the European Space Agency’s XMM-Newton satellite.

“We understand that there’s a bit of skepticism,” Lisse says. “We’re going to do some follow-up with a totally different instrument to verify this.”

X-rays from Pluto aren’t just a quirky detail about this specific dwarf planet. If other bodies in the Kuiper belt, the ring of icy debris just past Neptune’s orbit, have atmospheres, then X-ray observations could help detect them.

609

EEE / How a ring of mountains forms inside a crater

« on: November 20, 2016, 06:04:09 PM »

Building mountains in minutes requires deep rocks and a big bang.

Rings of mountainous peaks sit inside large impact craters, but scientists weren’t sure how these features formed. One explanation proposed that these mountains form from deep rocks jolted to the surface by the impact. Another theory suggested that uplift caused surface rocks to congregate in heaps around the crater.

Rocks extracted from ground zero of the impact that devastated the dinosaurs have now resolved this debate. That crater’s peak ring is made up of deep rocks, researchers report in the Nov. 18 Science.

Confirming this explanation of peak ring formation will help scientists study the depths of other planets, says study coauthor Sean Gulick, a geophysicist at the University of Texas at Austin. It will also help better estimate the environmental damage wrought by the dinosaur-killing impact.

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EEE / There’s something cool about Arctic bird poop

« on: November 20, 2016, 06:01:23 PM »

Seabird poop helps the Arctic keep its cool, new research suggests.

The droppings release ammonia into the atmosphere, where it reacts with other chemicals in the air to form small airborne particles. Those particles form the heart of cloud droplets that reflect sunlight back into space, researchers propose November 15 in Nature Communications.

Even though the poop’s presence provides only modest cooling, understanding the effect could help scientists better predict how the region will fare under future climate change, says study coauthor Greg Wentworth. “The humor is not lost on me,” says Wentworth, an atmospheric chemist at Alberta Environment and Parks in Canada. “It’s a crucial connection, albeit somewhat comical.”

Arctic air temperatures are rising about twice as fast as temperatures in lower latitudes (SN: 12/26/15, p. , a shift that could threaten ecosystems and alter global weather patterns. Scientists still don’t fully understand Arctic climate, though.

Earlier this year, Wentworth and colleagues reported finding surprisingly abundant ammonia in Arctic air. They linked the chemical to the guano of the tens of millions of seabirds that flock to the frigid north each summer. Bacteria in the Arctic dine on the feces and release about 40,000 metric tons of ammonia annually. (The smell, Wentworth says, is awful.)

Once in the atmosphere, that ammonia reacts with sulfuric acid and water to form small particles that increase the number of cloud droplets, the researchers now propose. A cloud made up of a lot of smaller droplets will have more surface area and reflect more sunlight than a cloud made up of fewer but larger droplets.

This effect causes on average about 0.5 watts of summertime cooling per square meter in the Arctic, with more than a watt of cooling per square meter in some areas, the researchers estimate using a simulation of the Arctic’s atmospheric chemistry. For comparison, the natural greenhouse effect causes about 150 watts of warming per square meter worldwide. On top of that, carbon dioxide from human activities currently contributes about 1.6 watts per square meter of warming on average.

“Birds are in the equation now” when it comes to cloud formation, says Ken Carslaw, an atmospheric scientist at the University of Leeds in England. Understanding how climate change and human activities in the Arctic impact seabirds could be important to forecasting future temperature changes in the region, he says.

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EEE / Double-charging material makes a run in the sun extra powerful

« on: November 20, 2016, 05:59:57 PM »

A self-charging textile captures both solar and mechanical energy to power wearable electronic devices — no bulky batteries needed. The top layer contains thin, flexible solar cells woven into a material that harvests energy from the sun. The bottom layer is made from similarly pliable supercapacitors that store the energy for later use, researchers report October 26 in Science Advances.

Here’s the cool part: As the person wearing the material moves, the two layers of fabric rub together and build up static electricity. The supercapacitors stockpile that energy, too. Harnessing two energy sources provides more consistent power than relying on solar cells alone, says study leader Zhong Lin Wang of Georgia Tech in Atlanta. The prototype textile — a 13-centimeter-square swatch — can power an LED or a digital watch, but the researchers hope it could someday charge more energy-intensive electronic devices such as fitness trackers or MP3 players.

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EEE / Sounds and glowing screens impair mouse brains

« on: November 20, 2016, 05:58:19 PM »

Mice raised in cages bombarded with glowing lights and sounds have profound brain abnormalities and behavioral trouble. Hours of daily stimulation led to behaviors reminiscent of attention-deficit/hyperactivity disorder, scientists reported November 14 at the annual meeting of the Society for Neuroscience.

Certain kinds of sensory stimulation, such as sights and sounds, are known to help the brain develop correctly. But scientists from Seattle Children’s Research Institute wondered whether too much stimulation or stimulation of the wrong sort could have negative effects on the growing brain.

To mimic extreme screen exposure, mice were blasted with flashing lights and TV audio for six hours a day. The cacophony began when the mice were 10 days old and lasted for six weeks. After the end of the ordeal, scientists examined the mice’s brains.

“We found dramatic changes everywhere in the brain,” said study coauthor Jan-Marino Ramirez. Mice that had been stimulated had fewer newborn nerve cells in the hippocampus, a brain structure important for learning and memory, than unstimulated mice, Ramirez said. The stimulation also made certain nerve cells more active in general.

Stimulated mice also displayed behaviors similar to some associated with ADHD in children. These mice were noticeably more active and had trouble remembering whether they had encountered an object. The mice also seemed more inclined to take risks, venturing into open areas that mice normally shy away from, for instance.

Some of these results have been reported previously by the Seattle researchers, who have now replicated the findings in a different group of mice. Ramirez and colleagues are extending the work by looking for more detailed behavioral changes.

For instance, preliminary tests have revealed that the mice are impatient and have trouble waiting for rewards. When given a choice between a long wait for a good reward of four food pellets and a short wait for one pellet, stimulated mice were more likely to go for the instant gratification than non-stimulated mice, particularly as wait times increased.

Overstimulation didn’t have the same effects on adult mice, a result that suggests the stimulation had a big influence on the developing — but not fully formed — brain.

If massive amounts of audio and visual stimulation do harm the growing brain, parents need to ponder how their children should interact with screens. So far, though, the research is too preliminary to change guidelines (SN Online: 10/23/16).

“We are not in a position where we can give parents advice,” said neuroscientist Gina Turrigiano of Brandeis University in Waltham, Mass. The results are from mice, not children. “There are always issues in translating research from mice to people,” Turrigiano said.

What’s more, early sensory input may not affect all children the same way. “Each kid will respond very, very differently,” Turrigiano said. Those different responses might be behind why some children are more vulnerable to ADHD.

There’s still much scientists don’t understand about how sensory input early in life wires the brain. It’s possible that what seems like excessive sensory stimulation early in life might actually be a good thing for some children, sculpting brains in a way that makes them better at interacting with the fast-paced technological world, said Leah Krubitzer of the University of California, Davis. “This overstimulation might be adaptive,” she said. “The benefits may outweigh the deficits.”

613

EEE / Surprising number of meteoroids hit moon’s surface

« on: November 20, 2016, 05:57:43 PM »

The moon is one tough satellite. With no atmosphere, it endures a barrage of incoming asteroids and comets that pit its surface with a constellation of craters. A new map (above) reveals 222 recent impact craters (in yellow), 33 percent more than simulations predicted. Scientists spotted the features by analyzing about 14,000 pairs of before-and-after images captured by the Lunar Reconnaissance Orbiter from 2009 to 2015. (Red dots note new craters whose impacts were observed from Earth.)

The craters — up to 43 meters in diameter — were probably formed by small meteoroids crashing into the crust. Using the image pairs, the researchers created ratio images, which highlight how the impacts alter the reflectance of the moon’s surface. That perspective illuminated the starburst debris patterns around the craters (below, left).

The scientists also found about 47,000 “splotches,” faint marks several to tens of meters across (below right, before and after shown). Most result from secondary debris being jettisoned by impacts and spattering the surface, the researchers propose in the Oct. 13 Nature.

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EEE / Dinosaurs may have used color as camouflage

« on: November 20, 2016, 05:56:44 PM »

The stories of dinosaurs’ lives may be written in fossilized pigments, but scientists are still wrangling over how to read them.

In September, paleontologists deduced a dinosaur’s habitat from remnants of melanosomes, pigment structures in the skin. Psittacosaurus, a speckled dinosaur about the size of a golden retriever, had a camouflaging pattern that may have helped it hide in forests, Jakob Vinther and colleagues say.
The dinosaur “was very much on the bottom of the food chain,” says Vinther, of the University of Bristol in England. “It needed to be inconspicuous.”

Identifying ancient pigments can open up a wide new world of dinosaur biology and answer all sorts of lifestyle questions, says zoologist Hannah Rowland of the University of Cambridge. “You might be able to take a fossil … and infer a dinosaur’s life history just from its pigment patterns,” she says. “That’s the most exciting thing.”

Not so fast, says paleontologist Mary Schweitzer of North Carolina State University in Raleigh. Evidence for ancient pigments can be ambiguous. In some cases, microscopic structures that appear to be melanosomes may actually be microbes, she says. “Both hypotheses remain viable until one is shot down with data.” Until then, she says, inferring dinosaur lifestyles from alleged ancient pigments is impossible.

Vinther’s work, published in the Sept. 26 Current Biology, is the latest in a long-simmering debate in the field of paleo color, the study of fossil pigments and what they can reveal about ancient animals. Disputes over his team’s findings and what’s needed to clearly identify fossilized melanosomes point to current pitfalls of the field.

But the promise is clear: Paleo color could paint a vivid picture of a dinosaur’s life, offering clues about behavior, habitat and evolution.

“This is a crucial new piece in the puzzle of how the past looked,” Vinther says.

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EEE / Despite Alzheimer’s plaques, some seniors remain mentally sharp

« on: November 20, 2016, 05:54:04 PM »

A small number of people maintain razor-sharp memories into their 90s, despite having brains chock-full of the plaques and tangles linked to Alzheimer’s disease. Researchers suspect that these people’s brains are somehow impervious to the usual devastation thought to be caused by those plaques and tangles.

Researchers studied the brains of people 90 years old or older who had excellent memories, performing as well as people in their 50s and 60s on some tests. Postmortem brain tissue from eight such people revealed a range of Alzheimer’s features. Two participants had remarkably clean brains with few signs of amyloid-beta plaques and tangles of tau protein. Four participants had middling levels.

Surprisingly, the other two samples were packed with plaques and tangles, enough to qualify those people for an Alzheimer’s diagnosis based on their brains. “These people, for all practical purposes, should be demented,” study coauthor Changiz Geula of Northwestern University’s medical school said November 15 in a news briefing at the annual meeting of the Society for Neuroscience.

Further tests revealed that even in the midst of these Alzheimer’s hallmarks, nerve cells survived in people with strong memories. Those people had more healthy-looking nerve cells than people with dementia and similar plaque and tangle levels. The researchers don’t know how these mentally sharp people avoid the ravages thought to be caused by plaques and tangles. “What’s surprising is this segment of people does exist,” Geula says. “We have to find out why.”