Astronomy
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Snake Rovers Might be the Best Way to Explore the Surface and Tunnels on Mars
Human space exploration is going to kick into high gear in the coming decades. Within the inner Solar System alone, missions are being planned that will see robotic explorers and crews sent to Near Earth Objects (NEOs), back to the Moon, and even on to Mars. Beyond that, there are even plans to send robotic missions to Europa, Enceladus, Titan, and other “ocean worlds” to look for signs of life.
In all cases, questions natural arise as to what kinds of missions will be most suited to them. In the case of places like Titan (which have low gravity and dense atmospheres) aerial drones are considered the best bet. But when it comes to rocky place like asteroids, the Moon and Mars, the best candidate may be robot snakes, which could find their way through tight spaces and travel underground.
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As Transeth explained back in 2013, this pairing would open up all kinds of possibilities. “We are looking at several alternatives to enable a rover and a robot to work together,” he said. “Since the rover has a powerful energy source, it can provide the snake robot with power through a cable extending between the rover and the robot. If the robot had to use its own batteries, it would run out of power and we would lose it.”
In the configuration Transeth and his colleagues are envisioning, the rover would handle the task of traveling over long distances and then be able to dispatch the snake to crawl into tight inaccessible areas. They would be connected by a cable that would provide electricity, communication signals and would be used to pull the snake back in. In this sense, the snake would act like one of the rover’s arms, but would have the ability to travel autonomously.
“We believe that we can design a robot that can hold on, roll itself up and then extend its body in order to reach new contact points,” said Transeth. “Moreover, we believe that it can creep in among equipment components on the ISS and use equipment surfaces to gain traction in order to keep moving forward – much in the same way as real snakes do in the wild.”
The Fate of NASA’s Dawn Spacecraft is Still Undecided
NASA’s Dawn spacecraft is low on hydrazine fuel and missing some wheels, but its fate after its current mission ends June 30 is still being decided.
The solar-powered spacecraft was launched back in September 2007 to study protoplanets in the asteroid belt, asteroid Vesta, and dwarf planet Ceres. Dawn arrived at Ceres in March 2015 and became the first spacecraft to visit a dwarf planet, beating New Horizons’ visit to Pluto by just four months.
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During this mission, Dawn ended up losing three of its four reaction wheels, which are used to control what the spacecraft points at. Carol Raymond, deputy principal investigator at NASA’s Jet Propulsion Laboratory, told SpaceFlightNow that the loss of the third wheel was may not end the mission, but it does have an impact on the amount of time Dawn has left.
With missing wheels and low fuel, the teams are weighing the financial costs of Dawn and the scientific payoff to decide what to do with Dawn come June 30. The options right now are to stay at Ceres, send Dawn off on another object, or just shut the craft down altogether.
Dawn uses more hydrazine to control the craft’s orientation when it’s closer to Ceres and when it’s in lower orbits, so sending it off on another mission might preserve fuel, but the final decision will be up to NASA.
Biology
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Bee Antennae Offer Links Between the Evolution of Social Behavior and Communication
An international team of researchers, including those from Princeton University, reported that a certain species of bees, called halictid bees, have more sensorial machinery compared with related solitary species. The difference is measured by the density of tiny, hollow sensory hairs called sensilla on their antennae.
[Sarah Kocher, an associate research scholar at the Lewis-Sigler Institute for Integrative Genomics and the paper’s corresponding author] and her colleagues imaged the antennae of adult females from 36 species that Kocher netted in the wild, mostly in France, or secured from specimens from the Museum of Comparative Zoology in the Department of Organismic and Evolutionary Biology at Harvard University and the American Museum of Natural History in New York. Using a scanning electron microscope at Princeton, they obtained information about the antennae’s surface topography and composition and observed convergent changes in both sensilla structures and the chemical signals of the groups as sociality was gained and lost.
Kocher and her colleagues chose to examine halictid bees because they exhibit remarkable diversity in social behavior, from eusocial to solitary. Eusocial refers to an organizational structure in which individual insects in a colony forgo their reproductive capacity and perform a specific task, such as caring for young or gathering food, as seen in many ant, wasp and honeybee species. Also, within this family of insects, social behavior has evolved independently several times, and there are numerous examples of reversion, or a reappearance of an earlier physical characteristic, and replicated losses of sociality. These repeated gains and losses make the species one of the most behaviorally diverse social insects on the planet, and good candidates for studying sociality, according to Kocher. “What we have is a system with tremendous comparative power,” she said.
Relatively little is known about the evolutionary transition between solitary and social living, according to Kocher. But in this paper, “[The researchers] provide an elegant solution to this problem,” said Tom Wenseleers, a professor of evolutionary biology at the University of Leuven in Belgium who is familiar with the research but had no role in it. “By studying a group of primitively eusocial insects that evolved sociality more recently and on several occasions reverted back to a solitary lifestyle, [they] succeed in making an accurate comparison of the investment in chemosensory systems made by social and derived, closely related, nonsocial species.”
In the paper, the researchers also noted that ancestrally solitary halictid bees — those bees that had never evolved social behaviors — had sensilla densities similar to eusocial species, while secondarily solitary halictid bees — those bees that evolved from social to solitary and back — exhibited decreases in sensilla density. Kocher was surprised by these patterns, but concluded that “sensilla density may be an important precursor to the evolution of social behavior.”
When Lovers Touch, Their Breathing, Heartbeat Syncs, Pain Wanes
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Scientists have long known that people subconsciously sync their footsteps with the person they're walking with or adjust their posture to mirror a friend's during conversation. Recent studies also show that when people watch an emotional movie or sing together, their heart rates and respiratory rhythms synchronize. When leaders and followers have a good rapport, their brainwaves fall into a similar pattern. And when romantic couples are simply in each other's presence, their cardiorespiratory and brainwave patterns sync up, research has shown.
The new study, co-written with University of Haifa Professor Simone Shamay-Tsoory and Assistant Professor Irit Weissman-Fogel, is the first to explore interpersonal synchronization in the context of pain and touch. The authors hope it can inform the discussion as health care providers seek opioid-free pain relief options.
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Men were assigned the role of observer; women the pain target. As instruments measured their heart and breathing rates, they: sat together, not touching; sat together holding hands; or sat in separate rooms. Then they repeated all three scenarios as the woman was subjected to a mild heat pain on her forearm for 2 minutes.
As in previous trials, the study showed couples synced physiologically to some degree just sitting together. But when she was subjected to pain and he couldn't touch her, that synchronization was severed. When he was allowed to hold her hand, their rates fell into sync again and her pain decreased.
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Further research is necessary to figure out how a partner's touch eases pain. Goldstein suspects interpersonal synchronization may play a role, possibly by affecting an area of the brain called the anterior cingulate cortex, which is associated with pain perception, empathy, and heart and respiratory function.
Chemistry
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Gallium Nitride
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A relatively modern material, gallium was discovered in 1875 and instantly slotted into a gap in Mendeleev’s periodic table, exhibiting the predicted physical properties of his ‘eka-aluminium’. Gallium nitride meanwhile, rose to fame in the ‘60s, upon the growth of its first single crystal films. A combination of group III and V elements, gallium nitride is isoelectronic to the elemental semiconductor germanium, but differs in its structure and band gap. Scientists were excited to explore its properties.
One of the properties of gallium nitride was that it readily transformed electrical energy into a dim blue light, a much sort-after colour for LEDs. It was also found to be tolerant to a wide range of temperatures, resistant to ionising radiation and less reactive to the atmosphere than other group III-V compounds, making it easier to use. Crucially, it showed a low electrical resistance, losing only a small proportion of power as heat and so allowing it to handle ten times the voltage of silicon, making smaller, faster, and more efficient devices.
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It also suffered from a major hitch: gallium nitride transistors never turned off. The neurons of computer signalling, transistors are designed to let high currents flow and block high voltages – but gallium nitride transistors flowed all the time, like a constant stream of adrenaline, risking a short circuit.
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Today, the main obstacle for gallium nitride is cost. Already, it appears in devices from blu-ray readers to photocatalysts, and is involved in the electrolysis of water. In the future, its use with LED lights could produce 70% to 80% efficiency. It could be used to make smaller laptop power adaptors , more compact solar cells on satellites, or to produce tetrahertz radiation for medical imaging, body scanning or spying. Single crystal gallium nitride nanotubes and nanowires have further applications in micro- and optoelectronics. These tiny materials, as a result of their large surface to bulk ratios, are subject to quantum effects and may have very different properties to the bulk materials.
As it becomes cheaper to make, gallium nitride could be used to run Google, detect skin cancer, and, by reducing battery weight and increasing battery capacity, it could even take you to the shops in the next generation of electric vehicles.
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Ecology
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Storms Caused Massive Antarctic Sea Ice Loss in 2016
Antarctic sea ice – frozen ocean water that rings the southernmost continent – has grown over the past few decades but declined sharply in late 2016. By March of 2017 – the end of the Southern Hemisphere’s summer – Antarctic sea ice had reached its lowest area since records began in 1978. [...]
In the study, British Antarctic Survey (BAS) scientists puzzled by the sudden ice loss matched satellite images of Antarctica with weather data from the second half of 2016 to figure out what caused so much of the ice to melt. They found that a series of remarkable storms during September, October and November brought warm air and strong winds from the north that melted 75,000 square kilometers (30,000 square miles) of ice per day. That’s like losing a South Carolina-sized chunk of ice every 24 hours.
“Antarctic sea ice is relatively thin – on average only 1 meter (3 feet) thick – making it extremely vulnerable to strong winds, says lead author John Turner, a climate scientist at BAS.
He continues: “The sea ice area is an important indicator of climate change, and sea ice loss in the Arctic has been linked to increased greenhouse gas emissions. But because sea ice records go back only four decades – when the satellite era began – it’s difficult to attribute Antarctica’s sea ice loss last year to human-caused climate change, Whaling records provide scientists with hints of Antarctica’s past sea ice extent, but it’s tough to compare that data to satellite records. There’s no indication this is anything but just natural variability. It highlights the fact that the climate of the Antarctic is incredibly variable.”
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Up until this most recent decline, the area of Antarctic sea ice had increased slightly since satellite records began in the late 1970s. But that increase doesn’t mean climate change hasn’t affected Antarctica, says Walt Meier, a sea ice scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, who was not connected to the study.
Measuring Biological Dust in the Wind
In the popular children’s story “Horton Hears a Who!” author Dr. Seuss tells of a gentle and protective elephant who stumbles upon a speck of dust that harbors a community of microscopic creatures called the Whos living the equally tiny town of Whoville. Throughout their journey together, Horton argues for the existence of the Whos traveling around in the air on a dust speck, while doubters dispute the finding. Ultimately, through observation, evidence for the organisms emerges, but regardless of the outcome, this speck altered a world greater than its own.
While this tale is a work of fiction, climate and atmospheric scientists have considered a real-life Whoville scenario — biological particles and inorganic material riding around in the atmosphere affecting the climate. Previous research has shown that some aerosols are very good at nucleating ice, which could form clouds in the troposphere. But due to complex atmospheric chemistries and a lack of data, scientists aren’t sure what percentage of these ice active particles are biological in nature and abundant enough in the troposphere to have an impact on climate. Furthermore, chemically parsing the metaphorical Whos from their speck has proved difficult — until now.
Atmospheric science researchers in the Program in Atmospheres, Oceans and Climate (PAOC) in MIT’s Department of Earth, Atmospheric and Planetary Sciences (EAPS) have found a way to differentiate biological material in the atmosphere (bioaerosols) from non-biological particulates with a higher accuracy than other methods, using machine learning. When applied to previously-collected atmospheric samples and data, their findings support evidence that on average these bioaerosols globally make up less than 1 percent of the particles in the upper troposphere — where they could influence cloud formation and by extension, the climate — and not around 25 to 50 percent as some previous research suggests.
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The unlikeliness of a real-life Whoville
While the list of bioaerosols tested and data sets used — which didn’t include locations and times of high and low bioaerosol concentration — were not exhaustive, the group found convincing evidence that, when it came to cirrus cloud formation, bioaerosols were an unlikely culprit. Previous research assumed that most of the phosphorus found in the atmosphere was biological, but [MIT associate professor of atmospheric chemistry Dan Cziczo] points out that this conflicts with phosphorus emissions inventories, implying that inorganic compounds were often mistaken for biological ones. For Cziczo this finding that bioaerosols accounted for less than 1 percent on average was the smoking gun.
“It’s not enough to say that a particle is good at nucleating ice, it also has to have an abundance that causes that cloud formation to happen. And it looks much less certain now that we have enough of these biologicals to create the effect that some people have suggested in the literature,” Cziczo says. “Instead, it’s much more likely that there are other things that are causing the ice nucleation like the mineral dust particles.”
Physics
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Artificial Iris Responds To Light On Its Own
While the pupil may be the opening in the eye that lets light through to the retina, the iris is the tissue that opens and closes to determine the size of the pupil. Although mechanical irises are already a standard feature in cameras, scientists from Finland and Poland have recently created an autonomous artificial iris that's much more similar to those found in the eye – it may even eventually be able to replace damaged or defective ones.
The contact lens-like device was created by researchers from Finland's Tampere University of Technology, along with Poland's University of Warsaw and Wrocław Medical University.
It's made from a polymer (a liquid crystal elastomer) that expands when exposed to light, then shrinks back when the light is lessened. This causes an opening in the middle to get smaller or larger, depending on the light levels – in this way, it works very much like a natural iris. Unlike automatic irises in cameras, it requires no power source or external light detection system.
With an "eye" towards one being able to use it as an optical implant, the scientists are now adapting it to work in an aqueous environment. They're also working at increasing its sensitivity, so that its opening and closing are triggered by smaller changes in the amount of incoming light.