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Updated: 5 hours 2 min ago

Earth’s ancient atmosphere may have been much thinner

10 May 2016
New Scientist: The atmosphere on Earth some 2.7 billion years ago may have been less than half as thick as it is today. That finding is based on a new study in which Sanjoy Som of NASA’s Ames Research Center and colleagues looked at gas bubbles trapped in ancient lava covering thousands of square kilometers in the Australian outback. By comparing the larger bubbles that rose to the top with the smaller ones that got trapped at the bottom, the researchers were able to determine that the air pressure billions of years ago when the lava hardened was probably 0–0.5 atmospheres; the best estimate is that the atmosphere was 23% as thick as it is today. That finding contradicts earlier theories that said the atmosphere must have been thicker to prevent Earth’s surface from freezing over when the Sun was much younger and fainter. The researchers say the key may be nitrogen, which might have dominated the primeval atmosphere, warming it and fueling nascent microbial life.

Space agencies develop plan for network of emissions-tracking satellites

10 May 2016
New York Times: The space agencies of China, France, India, the US, and several other countries have distributed a draft of a plan that calls for six to eight satellites to map carbon dioxide emissions with enough precision to identify individual nations as the source. The satellite array, which is estimated will cost $5 billion and be in orbit by 2030, would be similar to the network of satellites that monitors cloud cover. The ability to measure the emissions contributions from individual countries would be a major improvement over the current system of self-reported values based on surface readings, economic analyses, and ecological estimates. In the current system, established in 1992, industrialized nations report yearly but developing nations only have to report occasionally. However, in the 2000s, emissions from developing nations surpassed those of industrial nations and currently are estimated to be 60% of the annual global emissions total.

<em>LRO</em> team asks NASA to extend mission another two years

10 May 2016
Science News: Launched in 2009 for a one-year expedition to study the Moon, the Lunar Reconnaissance Orbiter (LRO) has had its mission extended repeatedly over the last seven years. Mission researchers have completed the primary goals of scouting potential future landing sites for astronauts, looking for water, and probing radiation hazards. LRO is now the longest-lived lunar orbiter, and the team hopes to add at least two more years. Over its extended mission LRO has watched three other spacecraft crash into the Moon's surface, mapped numerous craters, spotted water ice covered by the Moon's regolith, and found evidence of past volcanic activity.

Magnetically levitated, tube-based transportation system would travel at rocket speed

10 May 2016
IEEE Spectrum: Passive magnetic levitation is the key to a proposed next-generation high-speed mass transit system. Hyperloop Transportation Technologies (HTT), a startup based in Southern California, is working on the concept with scientists from Lawrence Livermore National Laboratory, where the technology was first developed. The HTT system would consist of a magnetically levitated capsule that travels at the speed of sound inside a reinforced vacuum tube laid atop pylons. Levitation is achieved by lining the bottom of the capsule with a Halbach array of permanent magnets and running it over a railbed of electromagnetic coils. Such a system could cut travel times between major cities significantly. According to the HTT website, commuters would be able to go from New York City to Washington, DC, in just half an hour. Said to be cheaper and safer than active magnetic levitation systems, such as MagLev, which require power stations along the track, the HTT system is one of several levitated trains currently in development.

Monsoon season may not provide drought relief in India

9 May 2016

CNN: India is experiencing its worst drought in decades. Exceptionally high temperatures some 3–5 °C above average over the past year and two years of below-average rainfall have severely reduced groundwater levels. According to India's Central Water Commission, the country's major water reservoirs are 79% empty, and three-quarters of the country's basins have less water than the 10-year average. They are so depleted that the next monsoon season, which begins in June, will likely not be enough to fully replenish them, says Nitya Jacob of WaterAid India. 

Antarctic sediment core reveals ancient transition from greenhouse to icehouse

9 May 2016
New Scientist: A single marine sediment core has revealed Antarctica’s climatological history from tropical forest to icy wasteland, according to Ulrich Salzmann of Northumbria University in Newcastle upon Tyne, UK, and his colleagues. Collected from the seafloor off Wilkes Land in East Antarctica during the Integrated Ocean Drilling Program, the core contains pollen grains that indicate a change in vegetation between 54 million and 12 million years ago. During the Eocene epoch, when its temperature hovered around 16 °C, the continent was covered with lush tropical forests, which included palms and monkey puzzle trees. By the early Oligocene, those trees had been replaced by more temperate species, including pines, conifers, and beeches. By the Miocene, some 23 million years ago, temperatures had dropped to about 6 °C and mosses and similar tundra plants had begun to take over. All greenery disappeared around 12.5 million years ago when the glaciers took over. Understanding Antarctica’s climate history may become important as climate change causes the continent to once more warm up and its ice to melt. Salzmann and his team presented their work at the April meeting of the European Geosciences Union General Assembly in Vienna.

First full-planet topological map of Mercury released

9 May 2016

Mashable: On Friday, researchers from the Johns Hopkins University Applied Physics Laboratory released the first full-planet mapping of elevations on Mercury. The map was produced from data collected by the MESSENGER spacecraft, which finished its mission roughly one year ago. To produce the map, the scientists used more than one-third of the 300 000 images of Mercury taken by MESSENGER. From the images, the researchers calculated the average ground level and then measured the lowest and highest points on the planet, with the lowest point being 5.38 km below the average and the highest point 4.48 km above the average.

Mount St Helens earthquake activity does not necessarily mean eruption

9 May 2016
Discovery: Despite some 130 small earthquakes that have occurred since 14 March, Mount St Helens in Washington State is not likely to erupt anytime soon, according to the US Geological Survey (USGS). The earthquake activity is reminiscent of what occurred more than 35 years ago, when a series of small quakes starting in March 1980 preceded the cataclysmic 18 May eruption that killed 57 people. Earthquakes around a volcano are caused by magma bubbling up from deep within Earth and putting pressure on the surrounding rock layers, which can fracture and slip. The magma pools in underground chambers, where it can collect until there is enough pressure to erupt to the surface. Such recharging of a volcanic magma chamber, although worrisome, occurs over long periods of time. Similar seismic swarms occurred around Mount St Helens in 2013 and 2014. Nonetheless, the USGS continues to use its state-of-the-art volcano monitoring network to watch for any other signs, such as changes in gas emissions, shallow quakes, or crust deformation, that indicate a volcanic eruption is imminent.

How the bacterium <em>Pseudomonas syringae</em> induces water to crystallize

9 May 2016
The surface of a specialized protein arranges nearby water molecules to promote efficient ice formation.

Holdren lauds Obama’s science and technology accomplishments

6 May 2016
The president has been an unrelenting supporter of science throughout his two terms, his science adviser asserts.

Survey finds PhD students pursue postdoc positions by default

6 May 2016

New York Times: Generally a postdoctoral position is a stepping stone to a full-time position in academia, but academic positions are hard to come by because of low turnover and high competition. So why do so many doctoral students in the sciences pursue postdocs? In 2010 and again in 2013, Henry Sauermann of Georgia Tech and colleagues surveyed PhD students studying biological and life sciences, physics, chemistry, engineering, or computer science at 39 universities across the US. They found that more than three-quarters of the biological and life sciences students believed at least one year of postdoctoral research was necessary to apply for a faculty position, and by 2013, 74% had taken a postdoc position. In the other fields, 42% thought a postdoc was necessary for a faculty position, and 46% took a postdoc by 2013. The most common reason cited by students for taking a postdoc was to increase their chances of getting a desired job.

Unusual radar echoes in the sky may finally have been explained

6 May 2016

Science: For several decades, unusual radar signals have been spotted that appear at dawn at an altitude of 150 km, grow stronger as they descend to 20 km, and then rise back to 150 km before disappearing at sunset. Because the signals get weaker during solar eclipses and stronger during solar flares, the Sun may be the source of the effect. But what causes it has not been clear. Now Meers Oppenheim and Yakov Dimant of Boston University suggest that extremely high-energy solar UV radiation could be ionizing gas molecules in a thin band of the upper atmosphere at an altitude of 150 km. Earth's magnetic field would then cause the freed electrons and the ionized molecules to rearrange themselves into areas of varying density, which can be detected by radar.

Insect wings could serve as radiation dosimeters

6 May 2016
New Scientist: Dragonflies, houseflies, and other insects may one day be used to help gauge radiation levels at nuclear power plants and after nuclear incidents. Ionizing radiation causes electrons in the atoms of the insects’ wings to be ejected. The resulting holes can act as particles, which then move around the electrons. When exposed to UV light, the holes and electrons can recombine; when they do, a flash of light is emitted. Now Nikolaos Kazakis of the Athena Research Center in Greece and colleagues have tested the radiation sensitivity of several types of winged insects by exposing them to different doses, shining a light on them, and measuring the flashes. Because insects are short-lived, they are mostly uncontaminated by natural radiation. Although the researchers were able to measure exposures of 10–2000 Gy, the technique was not sensitive enough to detect lower radiation exposures. In addition, any exposure to sunlight reduced its effectiveness. However, say the researchers, the technique could still have its uses. And because insects are ubiquitous, there will always be plenty to be found in dark places such as air ducts and basements.

SpaceX lands rocket on ship at sea for second time

6 May 2016
Mashable: Earlier today SpaceX landed its first-stage Falcon 9 rocket on a drone ship in the Atlantic Ocean for the second time. The private aerospace company has attempted the feat six times so far, the last two of which have been successful. It has also landed the rocket on land once. A sea landing is preferred because it requires less fuel. Besides further demonstrating that the rocket can be recovered and reused, the mission successfully carried a Japanese communications satellite into orbit. After the landing, company CEO Elon Musk tweeted that the landing used three engines and had triple the deceleration of the previous flight. The ability to slow down quickly before landing would be useful for a future Mars expedition because of that planet’s thin atmosphere.

Chaos limits predictability of hurricane intensities

5 May 2016
If a butterfly sets off a hurricane halfway around the world, how well can we forecast the storm's strength?

Surgical robot performs first autonomous procedure

5 May 2016
GeekWire: The Smart Tissue Autonomous Robot (STAR) has succeeded in sewing up the ruptured intestines of four live piglets. STAR uses near-IR imaging to gauge the surgical site, a computer program to develop a surgical procedure, and a robotic arm to suture the cut ends together. Monitored by a team of human surgeons, STAR was able to operate fully autonomously about 60% of the time. Although STAR surpassed most human surgeons in quality of work, based on the spacing of the stitches and the tension on the sutures, it required twice the amount of time. Nevertheless, the experiment has been deemed an important proof of concept. Such robot surgeons would have several uses, including making the best surgical techniques more widely available and allowing difficult medical procedures to be carried out in isolated environments such as Antarctica or future outposts in deep space.

Machine learning algorithm creates successful chemical reactions from failed experiments

5 May 2016
Nature: Machine learning algorithms have been used to help create complex molecules based on input of known successful reactions. Now Alex Norquist, Sorelle Friedler, and Joshua Schrier of Haverford College in Pennsylvania and colleagues have included unsuccessful experiments in the data provided to a computer algorithm that predicts whether a specific set of reagents will react to form a crystalline material. The researchers provided the algorithm with data from nearly 4000 experiments, including both published successes and failed reactions, which they had to transcribe from unpublished notes. The team then asked the computer to identify the principles that distinguished the successful reactions from the failures. When subsequently provided with previously untried combinations of reactants, the algorithm suggested nearly 500 reactions, 89% of which resulted in a crystalline product. In comparison, the educated guesses of the researchers were successful only 78% of the time.

Explanation found for 2011 earthquake on US East Coast

5 May 2016

Gizmodo: The magnitude 5.8 earthquake that struck northern Virginia in 2011 was notable because of the extreme rarity of earthquakes in that region—it was the strongest earthquake east of the Rocky Mountains since 1944. The East Coast of the US is far from the edges of the North American tectonic plate, where interactions with neighboring plates trigger seismic activity. Now Berk Biryol of the University of North Carolina at Chapel Hill and colleagues believe they have found an explanation for the 2011 earthquake. Biryol's team used seismic activity from around the globe to construct a 3D map of the bottom of the North American plate. The researchers found that the southeastern part of the plate is heavily fractured and encompasses thin and thick sections of crust and mantle. Based on their map, the scientists argue that chunks breaking off the bottom of the plate could trigger earthquakes. The mechanism could explain other major seismic events such as the magnitude 8.1 earthquake that struck New Madrid, Missouri, and the 7.0 earthquake that struck Charleston, South Carolina, in the 1800s.

Canadian wildfire fueled by climate change

5 May 2016
Climate Central: On Tuesday some 80 000 residents of the city of Fort McMurray in Alberta, Canada, and the surrounding area were forced to evacuate when a wildfire lit up the skies and thick smoke filled the air. Unusually warm weather, with temperatures soaring into the 90s, and high winds helped fuel the flames. The fire, which has forced the largest evacuation in the area to date, is part of a growing trend. In Canada, wildfires are starting a month earlier and the average annual burn area has doubled since 1970, according to Mike Flannigan of the University of Alberta. Flannigan blames climate change, which has been causing drier winters and earlier spring snowmelt. A single wildfire in Canada can have global impacts because of the tons of carbon pollution that can be released into the atmosphere, which causes further warming and increased fire risk.

Stop falling in love with the latest Earth-like planet

5 May 2016
Extra Dimensions: Too many variables exist to confidently single out any newly discovered exoplanet as the go-to extrasolar destination.

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