Welcome to the Saturday Science Edition of Overnight News Digest
Overnight News Digest is a regular daily feature which provides noteworthy news items and commentary from around the world. The editorial staff includes side pocket, maggiejean, wader, Doctor RJ, rfall, and JML9999.
Neon Vincent is our editor-in-chief.
Special thanks go to Magnifico for starting this venerable series.
Astronomy
Scientists Find Ancient Lake On Mars
In 2010, scientists discovered an 18-square-mile chloride salt deposit on the surface of Mars. Found in the planet’s Meridiani region — near the Mars Opportunity rover’s landing site — this salt deposit sits in a low point in the Martian landscape. A new analysis now confirms that the deposit most likely formed at the bottom of an ancient lakebed, right around the time the Red Planet dried up. [...T]he feature is potentially an ancient impact crater that was degraded and filled by water. The water then evaporated and left the chloride behind. Dating a Lakebed Currently, we know of more than 600 salt deposits on the surface of Mars. But determining their ages has been challenging. Scientists determine the ages of features on Mars by counting the impact craters on that particular surface and then calibrating to the carefully dated rocks collected by the Apollo astronauts and the lunar crater record. The problem with the chloride deposits on Mars is that they are generally too small to have enough craters for an accurate age estimate. So the team used one of the oldest and most basic principles of geology: the principle of cross-cutting. This principle states that a geologic feature, such as a valley or a channel, cutting through a given terrain has to be younger than the terrain it cross-cuts — or at least the same age. In this instance, the outflow channel draining the depression cuts through a cratered landscape, enabling the team to estimate the channel’s age—and, therefore, the age of the lake it drained. The results of the analysis indicate that the lakebed is no older than 3.6 billion years old. However, this upper limit slightly contradicts the suggested time period when Mars is thought to have been warm enough to sustain large amounts of water on its surface, an era than ended roughly 100 million years prior. skyandtelescope
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'The Martian' Shows 9 Ways NASA Tech Is Headed To Mars
In the sci-fi film "The Martian," which hits theaters in October, astronaut Mark Watney (played by Matt Damon) is stranded by himself, and presumed dead, on the Red Planet. Watney must figure out a way to survive on the inhospitable planet, and somehow alert NASA that he is still alive so a rescue mission can be mounted. Fortunately, Watney is an engineer and knows how to adapt technology to fit his needs. But how much of the technology at Watney's disposal actually exists today, or should exist in the near future? Read on to learn about the tech NASA is developing as part of its effort to put real boots on Mars in the 2030s. 1. Human Habitats On Mars [...] NASA hasn't built a real Mars habitat yet, but the agency is simulating one using the two-story Human Exploration Research Analog at the Johnson Space Center in Houston. The facility can host astronauts for 14 days, and simulated mission times will soon be bumped up to 60 days. 2. A Mars Farm [...] In space, astronauts are starting to grow crops of their own. For example, astronauts aboard the International Space Station recently harvested the first lettuce leaves from the "Veggie" experiment, which is intended to help NASA learn how to establish and maintain off-Earth farms. 3. Water Recovery Watney also faces problems trying to conserve water on Mars. This same challenge confronts astronauts on the International Space Station, who recycle their urine, sweat and more for drinking water and other purposes. For future missions, NASA is trying to improve the filtration system so that astronauts will need fewer spare parts from Earth. space.com
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Biology
Study Shows Plant Species' Genetic Responses To Climate Change
A study by the University of Liverpool has found that the genetic diversity of wild plant species could be altered rapidly by anthropogenic climate change. Scientists studied the genetic responses of different wild plant species, located in a natural grassland ecosystem near Buxton, to a variety of simulated climate change treatments--including drought, watering, and warming--over a 15-year period. Analysis of DNA markers in the plants revealed that the climate change treatments had altered the genetic composition of the plant populations. The results also indicated a process of evolutionary change in one of the study species, suggesting that genetic diversity may be able to buffer plants against the harmful effects of climate change, allowing an "evolutionary rescue"
Dr Raj Whitlock, from the University's Institute of Integrative Biology, said: "Climate change is expected to present a significant challenge to the persistence of many populations of wild plant species. "Our understanding of the potential for such responses to climate change is still limited, and there have been very few experimental tests carried out within intact ecosystems. "We found that experimental climate change treatments can modify the genetic structure of plant populations within 15 years, which is very fast, in evolutionary terms. "Evolutionary flexibility within the plant populations at Buxton may help to explain why the grassland there has proven resistant to simulated environmental change."
biologynews.net
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How Termite Mounds ‘Breathe’
For decades, scientists have marveled at the towering mounds some termites construct and wondered how they work. Although it’s now widely believed the 1- to 2-meter-high structures (seen above) help with ventilation—exchanging stale air for fresh in the insect’s hidden nest—the mechanics behind such a system have remained a puzzle. Now, by using thermal imagery and installing tiny air-flow sensors in about two dozen termite (Odontotermes obesus) mounds, scientists think they have solved the mystery. Their investigation revealed that the mounds act like an “external lung,” harnessing the change in temperature as day becomes night to drive ventilation. Here’s how it works: Inside the hill is a large central chimney connected to a system of conduits located in the mound’s thin, flutelike buttresses. During the day, the air in the thin buttresses warms more quickly than the air in the insulated chimney. As a result, the warm air rises, whereas the cooler, chimney air sinks—creating a closed convection cell that drives circulation, not external pressure from wind as had been hypothesized. At night, however, the ventilation system reverses, as the air in the buttresses cools quickly, falling to a temperature below that of the central chimney. The reversal in air flow, in turn, expels the carbon dioxide–rich air—a result of the termites’ metabolism—that builds up in the subterranean nest over the course of the day, the researchers report online this week in the Proceedings of the National Academy of Sciences. Although the scientists only examined one termite species, the ventilation system is likely the same in others with similar mounds. Such insight could inspire developments in passive architecture, which seeks to eliminate the need for active heating and cooling systems in buildings using strategies such as natural ventilation and efficient insulation, the scientists say. sciencemag.org
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Chemistry
Neonicotinoids Present In Many US Streams
The US Geological Survey (USGS) is using its recent discovery of neonicotinoid insecticides in more than half of the urban and agricultural streams sampled across the US and Puerto Rico to push for new research into how these controversial pesticides affect marine organisms and those animals that feed on them. Neonicotinoids have been implicated in the decline in honey bees and other pollinators. The USGS research found at least one of a set of six neonicotinoids in 53% of the samples. Concentrations were generally low, but variations correlated well with agricultural patterns. No concentrations exceeded the US Environmental Protection Agency’s (EPA) safety criteria for aquatic life, and all detected neonicotinoids are classified as unlikely carcinogens in humans. During the study of 38 streams, conducted from 2011 to 2014, imidacloprid was detected in 37%, followed by clothianidin in 24%, thiamethoxam in 21%, dinotefuran in 13%, acetamiprid in 3%; thiacloprid was not found in any samples.
‘The occurrence of low levels in streams throughout the year supports the need for future research on the potential impacts of neonicotinoids on aquatic life and terrestrial animals that rely on aquatic life,’ said team leader Kathryn Kuivila, ‘and provides a baseline for that work.’
The White House released a strategy promoting honey bee health in May, which aimed to revisit neonicotinoid insecticide use. Mike Focazio, who coordinates the USGS toxic substances hydrology program, said the new research will support the goals of the administration’s strategy, by helping to understand whether these water-borne pesticides, particularly at low levels, threaten pollinators. However, Swiss agrochemical giant Syngenta – which manufactures thiamethoxam – remains skeptical, noting that detection is different from risk. ‘The thiamethoxam levels detected in US surface waters were infinitesimal and well below EPA’s maximum allowable concentration that is considered safe for plants and aquatic life,’ the company stated. rsc.org
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EU Agency Says Neonicotinoids Can Pose High Risks To Bees
Three neonicotinoid pesticides—clothianidin, imidacloprid, and thiamethoxam—may pose more of a risk to bees than previously thought, new studies by the European Food Safety Authority (EFSA) conclude. The studies find that in some cases spraying the chemicals onto the leaves of plants poses a high risk to bees and in other cases a high risk can’t be ruled out. [...] EFSA also reports that it was unable to complete assessments for some foliar spraying uses of the chemicals because of insufficient data. The studies prompted environmental groups to call for the European Union to extend a two-year ban on the use of the chemicals. Those restrictions went into effect in 2013, following assessments by EFSA that showed the three substances posed a high risk to bees when used as seed treatments or in granular form. cen.acs.org
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Earth Science
Oceans Will Rise Much More Than Predicted, NASA Says
The question is: How much higher will they go? NASA scientists are now warning that recent projections seem too conservative: Since 1992, sea levels have increased by an average of 3 inches around the world. Three years ago, the Intergovernmental Panel on Climate Change reported that by 2100 sea levels could rise 28 to 98 centimeters (11 to 38 inches), depending on the volumes of greenhouse gases emitted. Even if greenhouse gas emissions are stabilized and global warming is limited to no more than 2° C, the oceans could reach levels that would transform the world's coasts in the centuries ahead, NASA scientists say.
“With future warming, we may lock ourselves into multiple-meter sea level rise” over the coming centuries, says Eric Rignot, a glaciologist at NASA's Jet Propulsion Laboratory in Pasadena, California. “We're talking about 6 meters—18 feet—and higher of sea level rise. Sea level rise might rise half a meter per century, or several meters per century. We just don't know.”
nationalgeographic.com
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The Fingerprints of Sea Level Rise
When you fill a sink, the water rises at the same rate to the same height in every corner. That's not the way it works with our rising seas. According to the 23-year record of satellite data from NASA and its partners, the sea level is rising a few millimeters a year -- a fraction of an inch. If you live on the U.S. East Coast, though, your sea level is rising two or three times faster than average. If you live in Scandinavia, it's falling. Residents of China's Yellow River delta are swamped by sea level rise of more than nine inches (25 centimeters) a year. These regional differences in sea level change will become even more apparent in the future, as ice sheets melt. For instance, when the Amundsen Sea sector of the West Antarctic Ice Sheet is totally gone, the average global sea level will rise four feet. But the East Coast of the United States will see an additional 14 to 15 inches above that average. [...] Unless a volcano or earthquake is in the news, we tend to think of our home planet as solid rock. But 50 miles (80 kilometers) below our feet, there's a layer thousands of miles thick that can flow like a liquid over thousands of years. The tectonic plates of Earth's crust float on this viscous layer, called the mantle, like a vanilla wafer on a very thick pudding. If you were to put a strawberry on top of that vanilla wafer, the added weight would make the cookie sink into the pudding. In the same way, heavy weights on Earth's crust push it down into the mantle, which flows away and bulges out elsewhere. The miles-thick ice sheets of Greenland and Antarctica have been depressing the crust beneath them for millennia. That weight has a second effect that you won't see in your dessert: its gravitational pull on the surrounding ocean makes seawater pile up around the coastlines. jpl.nasa.gov
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Physics
IceCube Confirms Observation Of Astrophysical Muon Neutrinos
Because neutrinos have almost no mass and no electric charge, they can be very hard to detect and are only observed indirectly when they collide with other particles to create muons, telltale secondary particles. What’s more, there are different kinds of neutrinos produced in different astrophysical processes. The IceCube Neutrino Observatory records a hundred thousand neutrinos every year, most of them produced by the interaction of cosmic rays with the Earth’s atmosphere. Billions of atmospheric muons created in the same interactions also leave traces in the detector. And from all of these, physicists are looking for only a few dozen astrophysical neutrinos, which will expand our current understanding of the Universe. More than 35,000 neutrinos were found in data recorded by the IceCube between May 2010 and May 2012. However, only 21 of those neutrino events were clocked at energy levels indicative of astrophysical sources. sci-news.com
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Why Do Teapots Drip?
[...] In The Lab Scientists first thought the ‘teapot effect’ must be due to surface tension but, in 1956, Markus Reiner performed an experiment which seemed to show this wasn't true. He placed a conical flask upside down in water and poured salty water, which sinks in normal water because it’s denser, over the top of it. Since surface tension has no effect underwater the salty water stream should have fallen straight down from the edge of the flask’s bottom, but Reiner found that the water followed the incline of the flask for a short while. He also established that flow rate was important. The slower the pour, the more likely the teapot was to drip. With a fast pour the tea has less of a chance to slow down, change direction and drip down the spout. Next up to try and figure out why teapots drip was Joseph Keller, Professor of Mathematics and Mechanical Engineering at Stanford University and twice winner of the IgNobels. He reasoned it must be a combination of Bernoulli’s Principle and air pressure pushing on the water that caused it to run down the underside of the spout. And more recently, in 2009, French scientists discovered another part of the puzzle – the effect of wettability. Wettability is a measure of how much a liquid likes being in contact with a surface. At one end of the wettability scale are materials like clean glass, where water tends to spread out. At the other end are superhydrophobic materials. They occur naturally such as the lotus leaf, or, thanks to recent inventions, can be applied as a spray, making any material impervious to liquids or dirt. [...] So for most, dripping teapots are just a fact of life. But not for the housewives of the 1920s who knew how to change the wettability of surfaces and get rid of drips – by rubbing butter on the underside of the spout physics.org
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