Physics Today Daily Edition

Subscribe to Physics Today Daily Edition feed
Please follow the links to view the content.
Updated: 1 hour 20 min ago

Spacecraft observes aurora above Mars

19 March 2015
BBC: The Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft, launched by NASA in November 2013, has been exploring the Red Planet’s upper atmosphere since it arrived there in September 2014. As reported at the 46th Lunar and Planetary Science Conference being held this week in Texas, last December MAVEN detected the presence of a bright UV auroral glow in Mars’s northern hemisphere, similar to the northern lights that can be observed on Earth. However, the high-energy particles responsible for the phenomenon appear to penetrate much deeper into the atmosphere of Mars than they do on Earth, perhaps because Mars lacks Earth’s protective magnetic field. The aurora sighting, and the detection of dust at altitudes of 150–300 km, may help further MAVEN’s mission of determining how Mars’s atmosphere evolved.

Technology transfer gets new emphasis at DOE

19 March 2015
Under acting director Jetta Wong, the new office will broaden the paths to commercialization.

Harvesting satellite images for commercial use

18 March 2015
MIT Technology Review: Orbital Insight, a startup company founded by James Crawford, uses the vast amount of satellite imagery being collected to provide its clients with business and socioeconomic intelligence. The huge trove of data allows the company to monitor a number of activities, such as how many cars frequent a business’s parking lot each day, how much new construction is going on, and how quickly forests are being depleted. With the use of computer software and a new technique called deep learning, Orbital Insight looks for patterns in the satellite data and makes predictions about a range of industries. Its clients include real estate developers, insurance companies, and environmental nonprofits. The startup is one of a growing number of image-processing companies that are taking advantage of the ubiquitousness of modern satellite surveillance.

Bright spots on Ceres could be ice volcanos

18 March 2015

Nature: Several bright spots have been observed on the asteroid Ceres by NASA's Dawn spacecraft. The asteroid is known to have a significant amount of ice, but the way sunlight is being reflected indicates that the ice does not simply lie exposed on the asteroid's surface. New images from Dawn have revealed that some of the bright spots located in craters are still visible even when the crater walls should block them from the Sun. That observation suggests that, if the reflections are due to ice, the ice must have been pushed up to significant heights. One explanation could be volcano-like eruptions of the ice caused by fluctuating internal pressures within the asteroid. Similar eruptions could also be caused by sunlight warming the asteroid's surface as Ceres rotates from night to day, which could allow icy plumes to form that refreeze and then melt back down to the surface.

Solar gaining momentum in Europe and developing countries

18 March 2015

New York Times: Despite its reputation as a cool, cloudy country, the UK led Europe in the number of new solar installations in 2014. The combination of government subsidies and low prices because of high production rates from factories in China has driven the spread of solar in many European nations. And direct costs have now reached levels where solar can compete with natural gas without the need for subsidies. Thanks to those trends, European solar companies are building solar plants in developing nations such as Chile and India. In northern Chile, high altitude and low latitude allow solar to produce electricity at 80% the cost of coal, and 60% the cost of natural gas. Subsidies have even had some negative influences in the UK and Germany, where they've pushed up the cost of electricity overall. For large solar installations, the UK has begun auctioning guaranteed rates, which it believes will reduce the overall cost of electricity while still spurring solar growth.

Smaller solar-system body may sport Saturn-like rings

18 March 2015
Los Angeles Times: Centaurs, which are a relatively recent classification of a type of solar-system body, are a cross between an asteroid and a comet and orbit the Sun between Jupiter and Neptune. Not much is known about their origins, nor have any ever been photographed up close. In 2011, however, researchers were able to observe one such centaur, named Chiron, as it passed in front of a bright star. Chiron’s shadow indicated that the centaur is surrounded by an “optically thick material,” which astronomers propose could be a system of rings, like those that surround Saturn. Only five other bodies in our solar system are known to have rings, and it wasn’t thought that smaller bodies, like Chiron, would have them. Further observations will be necessary to support the theory.

<em>Washington Post</em> affirms a proposed “Reagan way” on climate

17 March 2015
The newspaper’s opinion editors, generally left-leaning overall, cheer for Republican statesman George Shultz’s op-ed.

Possible explanation for wind-like trails on comet surface

17 March 2015

BBC: When the European Space Agency's Rosetta was approaching comet 67P/Churyumov-Gerasimenko, its pictures of the cometary surface revealed 17 objects that appeared to have trails extending northward away from them. Such trails are common on Earth, where they are formed by wind depositing dust behind boulders or other objects. However, because the comet lacks an atmosphere, there isn't any wind. On Monday at the 46th Lunar and Planetary Science Conference, Stefano Mottola, the project leader of the Rosetta Lander Imaging System, announced that the team believes the trails were caused by splash saltation. The trails would have formed when objects impacted the surface and dislodged particles, which then fell back in the patterns seen.

New technique speeds up 3D printing significantly

17 March 2015

Nature: One of the common methods of 3D printing shines UV light into the bottom of a container of liquid resin, which causes the resin at the very bottom of the basin to solidify. The solid part must then be pulled up to allow new liquid resin to flow in underneath, and the process is repeated. Because of the need to pause after the creation of each layer, the process can take hours to days, depending on the size of the object being printed. Now, Joseph DeSimone of the University of North Carolina at Chapel Hill and his colleagues have developed a new printer that can produce objects in just minutes. They made a reservoir for the liquid resin that has a bottom permeable to oxygen. The oxygen keeps the resin at the bottom from solidifying, resulting in a micron-thick layer of resin that remains liquid beneath the printed object. That allows the object to be printed continuously, with no delays as it is pulled upward. The technique also allows for 3D printing using rubbery materials that did not work in previous machines.

Accelerating Antarctic glacier melt may be driven by deep-ocean processes

17 March 2015
Washington Post: Not only has the great ice sheet of West Antarctica begun to thaw, but one in East Antarctica may now be collapsing as well. The accelerated melting of the two ice sheets could cause global sea levels to rise by as much as 6 meters. To better understand the geography of the Totten Glacier of East Antarctica and the vast catchment of ice it contains, researchers from the US, the UK, France, and Australia compiled data gathered during research flights through the use of gravimetry, radar sounding, and laser altimetry. They discovered that the ice shelves extending out into the water may be becoming increasingly unstable because deep valleys on the seafloor could be collecting vast quantities of saltwater that is warmer and denser than the ice melt above it. To confirm their hypothesis, the researchers would like to launch robotic underwater vehicles that could directly measure the water's temperature, salinity, and other properties.

Ice propulsion system developed for CubeSats

17 March 2015
New Scientist: To help keep CubeSats and other types of nanosatellites in orbit longer, researchers at the Delft University of Technology in the Netherlands have designed a rocket propelled by ice. In space, water ice sublimates directly from a solid to a gas. As it does so, the released vapor molecules could be harnessed to create sufficient propulsion force for the satellite to correct its orbit or control its orientation. The use of ice as a propellant has several advantages over other fuel types: It is both nonexplosive and eco-friendly. A prototype of the researchers’ “micro-resistojet” is being developed for launch in a few years.

William M. Hooke

16 March 2015

DOE taps new director of Pacific Northwest National Laboratory

16 March 2015

Science: The Department of Energy has named Steven Ashby, a computational mathematician, as the next director of Pacific Northwest National Laboratory (PNNL). Before joining PNNL in 2008 as its deputy director for science and technology, Ashby worked for more than 20 years at Lawrence Livermore National Laboratory. PNNL, the second largest of DOE's 10 national laboratories, has a $1 billion budget, with funding from not only DOE's Office of Science but also the National Nuclear Security Administration and other sources. Ashby says the lab's primary mission is to "understand, predict, and control complex adaptive systems," including the climate, electrical infrastructure, and national security.

Carbon dioxide emissions remained stable in 2014

16 March 2015

BBC: The International Energy Agency (IEA) has announced that 2014 was the first time in 40 years, barring major economic downturns, that global carbon dioxide emissions did not increase. The data suggest that the steady levels were attributable to China's efforts to reduce coal consumption and other shifts in energy production in Organisation for Economic Co-operation and Development countries. The IEA says there have been three previous emissions slowdowns since it began taking records, but they were tied to economic events: the US recession in the early 1980s, the collapse of the Soviet Union in 1991, and the 2009 global recession.

Ancient conifer provides example of winged-seed evolution

16 March 2015
New Scientist: As early as 370 million years ago, conifer trees began to develop seeds with two wings, which enabled the seeds to catch the wind and travel farther from the parent tree. Over the next 100 million years, the seeds evolved to have just a single wing. Cindy Looy and Robert Stevenson of the University of California, Berkeley, caught a glimpse of that evolution in action through their study of one of the earliest known such conifers, Manifera talaris. Based on fossil evidence, they created paper models of the three known seed types—symmetric double-winged, asymmetric double-winged (with one large and one small, stunted wing), and single-winged. The researchers found that the single-winged seeds, which adopted an autorotating, helicopter-style spin, remained airborne the longest, and that the asymmetric double-winged seeds flew farther than the symmetric double-winged seeds.

Artificial chameleon

16 March 2015
Large refractive-index contrast and flexibility combine in a novel way to allow active control of perceived colors.

Congressional critic of NSF softens criticism of grant approval process

13 March 2015

Science: For the past two years, Representative Lamar Smith (R-TX) has criticized NSF for its peer-review-based grant approval process for funding research that does not support the national interest. Under his guidance a subcommittee of the House science committee has been examining a selection of grants issued by NSF over the past decade. However, in an interview on Wednesday, Smith said the investigation has led him to believe that NSF's grant approval process is indeed the best option for making such complex decisions.

Automated custom complex molecular synthesis

13 March 2015

Nature: Marty Burke of the University of Illinois at Urbana-Champaign and his colleagues have developed a system that may significantly simplify a time-intensive process for chemists: creating complex synthetic molecules. The computerized network of pumps and syringes manipulates a library of commercially available molecular compounds to combine them in the order programmed by the user. Similar techniques have been developed in the past, but Burke's machine includes a process that automates the removal of excess material and isolates the newly combined molecule for use in subsequent steps. The result is the first automatic system that can produce ring-shaped and branching molecules.

<em>Hubble</em> detects evidence of underground ocean on Ganymede

13 March 2015

BBC: Jupiter's Ganymede is the largest moon in the solar system and is also unusual in that it has a significant magnetic field. Joachim Saur of the University of Cologne in Germany and his colleagues have been using the Hubble Space Telescope to study Ganymede's magnetic field and aurora. The interactions between the magnetic fields of Jupiter and Ganymede cause wobbles in Ganymede's field that can be seen in the movements of the aurora. Saur's team compared their observations with various models of Ganymede's internal structure. They found that Jupiter's magnetic field creates a secondary fluctuation in Ganymede's aurora that would be easily explained by interacting with a body of saltwater. The Hubble data most closely match a model of the moon that includes a subsurface ocean, though that ocean could be anywhere from 100 km deep with a salt content of 5 kg/L to just 10 km deep with 50 kg/L salt concentration.

Wireless technique uses nanoparticles to stimulate brain

13 March 2015
New Scientist: Magnetic nanoparticles could one day replace the more invasive method of implanting electrodes to achieve deep brain stimulation. Polina Anikeeva of MIT and colleagues inserted the nanoparticles into the brains of three mice. When the researchers applied low-RF magnetic fields, the nanoparticles gave off heat as they worked to realign themselves. That heat prompted the brain’s TRPV1 neurons to fire and send out electrical signals. Unlike the use of electrodes, the new technique requires no implants or wires. Moreover, it could prove better at targeting specific areas of the brain, which is important for the treatment of such neurological disorders as Parkinson’s disease and depression.

Pages