NASA MAVEN Spacecraft Prepares for Mars Orbit-Insertion Maneuver

This artist concept depicts the process of orbital insertion of NASA’s Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft. Image Credit: NASA/GSFC

Launched last November, the MAVEN spacecraft is now preparing for an orbit-insertion maneuver that will allow the spacecraft to be pulled into an elliptical orbit of Mars with a period of 35 hours.

NASA’s Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft is nearing its scheduled September 21 insertion into Martian orbit after completing a 10-month interplanetary journey of 442 million miles.

Flight Controllers at Lockheed Martin Space Systems in Littleton, Colorado, will be responsible for the health and safety of the spacecraft throughout the process. The spacecraft’s mission timeline will place the spacecraft in orbit at approximately 9:50 p.m. EDT.

“So far, so good with the performance of the spacecraft and payloads on the cruise to Mars,” said David Mitchell, MAVEN project manager at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “The team, the flight system, and all ground assets are ready for Mars orbit insertion.”

The orbit-insertion maneuver will begin with the brief firing of six small thruster engines to steady the spacecraft. The engines will ignite and burn for 33 minutes to slow the craft, allowing it to be pulled into an elliptical orbit with a period of 35 hours.

Following orbit insertion, MAVEN will begin a six-week commissioning phase that includes maneuvering the spacecraft into its final orbit and testing its instruments and science-mapping commands. Thereafter, MAVEN will begin its one-Earth-year primary mission to take measurements of the composition, structure and escape of gases in Mars’ upper atmosphere and its interaction with the sun and solar wind.

“The MAVEN science mission focuses on answering questions about where did the water that was present on early Mars go, about where did the carbon dioxide go,” said Bruce Jakosky, MAVEN principal investigator from the University of Colorado, Boulder’s Laboratory for Atmospheric and Space Physics. “These are important questions for understanding the history of Mars, its climate, and its potential to support at least microbial life.”

MAVEN launched November 18, 2013, from Cape Canaveral, Florida, carrying three instrument packages. It is the first spacecraft dedicated to exploring the upper atmosphere of Mars. The mission’s combination of detailed measurements at specific points in Mars’ atmosphere and global imaging provides a powerful tool for understanding the properties of the Red Planet’s upper atmosphere.

“MAVEN is another NASA robotic scientific explorer that is paving the way for our journey to Mars,” said Jim Green, director of the Planetary Science Division at NASA Headquarters in Washington. “Together, robotics and humans will pioneer the Red Planet and the solar system to help answer some of humanity’s fundamental questions about life beyond Earth.”

The spacecraft’s principal investigator is based at the Laboratory for Atmospheric and Space Physics at University of Colorado, Boulder. The university provided two science instruments and leads science operations, as well as education and public outreach, for the mission.

NASA Goddard Space Flight Center in Greenbelt, Maryland, manages the project and also provided two science instruments for the mission. Lockheed Martin built the spacecraft and is responsible for mission operations. The Space Sciences Laboratory at the University of California at Berkeley provided four science instruments for MAVEN. NASA’s Jet Propulsion Laboratory in Pasadena, California, provides navigation and Deep Space Network support, and Electra telecommunications relay hardware and operations.

Construction to Begin on the Thirty Meter Telescope

The recent approval of a sublease brings the most advanced and powerful optical telescope, the Thirty Meter Telescope (TMT), one step closer to reality.

With the recent approval of a sublease by Hawaii’s Board of Land and Natural Resources, initial construction on the Thirty Meter Telescope — destined to be the most advanced and powerful optical telescope in the world — can now begin later this year.

The board’s final go-ahead, received July 25, moves the University of California and UCLA a step closer to peering deeper into the cosmos than ever before.

Work on the Thirty Meter Telescope (TMT), named for its 30-meter primary mirror — three times the diameter of the largest existing telescopes — will take place atop Hawaii’s dormant Mauna Kea volcano. The TMT’s scientific operations are slated to start in 2022.

Researchers in the UCLA College will play a significant role in the development and use of the TMT, which will enable astronomers to study stars and other objects throughout our solar system, the Milky Way and neighboring galaxies, and galaxies forming at the very edge of the observable universe, near the beginning of time.

The project is a collaboration among universities in the United States and institutions in Canada, China, India and Japan, with major funding provided by the Gordon and Betty Moore Foundation.

Thirty Meter Telescope (TMT) Overview

The project is a collaboration among universities in the United States and institutions in Canada, China, India and Japan, with major funding provided by the Gordon and Betty Moore Foundation.

“UCLA is taking a lead role in defining the science for this monumental, international project,” said Andrea Ghez, a professor of physics and astronomy who holds UCLA’s Lauren B. Leichtman and Arthur E. Levine Chair in Astrophysics.

Ghez, who has served on the TMT science advisory committee since its first meeting 13 years ago, described the master agreement as an important milestone for the UC system, UCLA and the field of astronomy.

“One reason why we want to build TMT is to delve into the most fundamental workings of our universe,” she said. “It is truly amazing to think about what TMT will teach us about the universe.”

Creating cutting-edge instruments for the TMT

UCLA professor of astronomy James Larkin is one of those excited about the TMT’s potential. He is the principal investigator for the Infrared Imaging Spectrograph (IRIS), one of three scientific instruments that will be ready for use with the TMT when the telescope begins operation.

“IRIS is an imaging spectrograph that perhaps can best be described as a sophisticated camera that takes small images at 2,000 different wavelengths simultaneously,” Larkin said. “Or it can be thought of as a spectrograph that takes 10,000 adjacent spectra over a rectangular area of the sky.”

The instrument will be able to produce images three times sharper than what is currently achievable with the two powerful W.M. Keck telescopes on Mauna Kea and many times sharper than the Hubble Space Telescope, Larkin said. IRIS will image planets that are forming but are often too dim and red to be detected by smaller telescopes, and it will be the only one of the three TMT instruments to magnify images to the theoretical diffraction limit.

“Exploring the universe at this unprecedented resolution and sensitivity means we will be surprised by what we find,” he said. “IRIS has a wide range of science objectives, ranging from chemical analysis of the surfaces of solar system moons like Titan and Europa, to following the evolution of galaxies over the past 13 billion years, to searching for the first stars in the very early universe.”

With the most sensitive spectroscopy available anywhere in the near-infrared, IRIS will yield the first real understanding the physical nature of these early galaxies, a key goal of research in cosmology and astrophysics.

IRIS is a joint project involving more than 50 astronomers from the U.S., Canada, Japan and China, and many of the instrument’s most crucial components will be designed and built at UCLA’s Infrared Laboratory for Astrophysics, founded more than 20 years ago by Ian S. McLean, who is the lab’s director and a UCLA professor of physics and astronomy.

The TMT, McLean said, will enable astronomers to see not only much fainter objects but also to resolve them in much greater detail.

“Both of these attributes are crucial for almost all of the frontier areas of modern astrophysics, from studies of nearby exoplanetary systems to probing the most distant objects in the universe,” he said. “The TMT is precisely the right kind of scientific tool to complement national facilities under development, such as the James Webb Space Telescope. We are all very excited that the TMT master agreement is signed.”

In 1989, at the beginning of the era of the twin W.M. Keck telescopes — currently the world’s largest optical and infrared telescopes — UCLA set up its infrared astrophysics lab to develop state-of-the-science instruments for them. All four of the currently operational infrared cameras and spectrometers on the Keck telescopes were built entirely or in part at UCLA. McLean expects UCLA’s infrared lab to play a similar role with the TMT.

The concept of a telescope three times larger and with nine times more light-gathering power than the Keck telescopes was first envisaged nearly 15 years ago, and UCLA has played a major role in defining the type of instruments needed for such a telescope. IRIS, under Larkin’s leadership, is one example, McLean said. Another proposed TMT instrument, the Infrared Multi-Slit Spectrometer (IRMS), will be a near-replica of the successful MOSFIRE instrument that McLean delivered to the W.M. Keck Observatory in 2012.

With the sharpest and most sensitive images ever taken in the near infrared, the TMT and IRIS will reveal the universe in new ways, exploring everything from dwarf planets at the orbit of Pluto to the most distant galaxies ever explored near the dawn of time, McLean said.

The twin 10-meter Keck telescopes have “attracted many distinguished faculty, trained students at all levels and served the people of California and the world with inspiring discoveries and technological leadership,” said McLean. “The University of California will continue that tradition of leadership and excellence with its participation in the TMT project, and UCLA will play a key role through the development and exploitation of infrared spectroscopy and high-resolution imaging technology.”

Solving the mysteries of black holes with the TMT

UCLA’s Ghez, who leads the development of the Galactic Center project, said her research will be greatly enhanced by the Thirty Meter Telescope.

Ghez and her colleagues discovered a supermassive black hole at the center of the Milky Way that has a mass approximately 4 million times that of our sun. Such mysterious and intriguing black holes, which were predicted by Einstein’s theory of general relativity, provide remarkable laboratories for the study of physics in extreme environments.

The TMT, Ghez said, will identify and map the orbits of fainter stars close to our black hole, extending our knowledge of physics with a fundamental test of Einstein’s theory. Because stars in the vicinity of the black hole will be affected by the presence or absence of dark matter, their orbits will significantly constrain our current model of dark matter, which is central to our understanding of galaxy formation.

TMT will also extend our ability to measure accurate masses of black holes in more distant galaxies and in low-mass galaxies, likely revealing when and how black holes are “fed,” Ghez said.

By revealing details about resolved stellar populations in nearby galaxies, the TMT and IRIS will directly probe the formation of nearby stellar systems like our own Milky Way. Because it will be possible to measure the mass distributions of stars in a variety of new environments and in galaxies outside of the Milky Way, IRIS will help scientists learn whether stars form differently under different conditions.

In the distant universe, IRIS’s ability to image and study the internal workings of early galaxies will represent a major breakthrough in the study of galaxy formation during the known peak period of star formation.

The Thirty Meter Telescope is a collaboration of the University of California, the California Institute of Technology, the Association of Canadian Universities for Research in Astronomy, the National Astronomical Observatory of Japan, a consortium of Chinese institutions led by the National Astronomical Observatories of the Chinese Academy of Sciences, and institutions in India supported by India’s Department of Science and Technology.

In addition to President Yudof, signatories of the TMT master agreement are Donald E. Brooks, chair of the institutional council of Association of Canadian Universities for Research in Astronomy; Jean-Lou Chameau, president of the California Institute of Technology; Masahiko Hayashi, director general of the National Astronomical Observatory of Japan; P. Sreekumar, director of the Indian Institute of Astrophysics; and Jun Yan, director general of the National Astronomical Observatories of China.

Intel co-founder Gordon Moore and his wife, Betty, established the Gordon and Betty Moore Foundation to support bold ideas that create enduring impact in science, environmental conservation and patient care.

‘Digital Metamaterials’ Bring Invisibility Cloaks Closer to Reality

A newly published study details how “digital metamaterials” could help bring invisibly cloaks closer to reality.

The concept of “digital metamaterials” – a simple way of designing metamaterials with bizarre optical properties that could hasten the development of devices such as invisibility cloaks and superlenses – is reported in a paper published today in Nature Materials.

Metamaterials are artificially engineered out of microscopic subunits – such as glass, metal or plastic – arranged in a repeating fashion. Once assembled, these metamaterials possess unique properties, such as interacting with light in unusual ways, which aren’t often seen in natural materials.

“The idea behind metamaterials is to mimic the way atoms interact with light, but with artificial structures much smaller than the wavelength of light itself,” said Boris Kuhlmey, associate professor of photonics and optics at the University of Sydney.

“This way, optical properties are no longer restricted to those of the constituent materials, and can be designed almost arbitrarily.”
The material world goes digital

The researchers of the Nature Materials paper, from the University of Pennsylvania, were inspired to develop digital metamaterials by the binary numeral system of Boolean algebra.

The binary system is used internally by most digital electronic devices, such as computers and smartphones. Complex digital devices have their digital information simply encoded as a string of 1s and 0s called “bits”.

The proposed method for digital metamaterials is a simplified way of building metamaterials, yet still allows for complex and diverse properties to be achieved.

“The beauty of the new method is its simplicity,” said Min Gu, professor of optoelectronics at Swinburne University of Technology.

Through the use of simulations in two-dimensional space, the researchers explored the possibility of creating metamaterials with only two specially chosen component parts, called metamaterial bits – analogous to the 1 and 0 “bits” of binary computer code. The arrangement of metamaterial bits represents the “digitizing” of metamaterials.

In their study, the researchers chose to use nano-sized pieces of silver and silica (glass) as their repeating metamaterial bits. These are materials that interact with light in very different ways on an individual level. Once they were “digitized”, the resulting metamaterial had its own unique properties, very different to those of its constituent parts.

“The components of the material work together to generate effects or give rise to phenomena that you wouldn’t observe if they weren’t arranged together in 3D (or in this case, 2D) space as an ordered assembly,” said Tiffany Walsh, professor of bionanotechnology at Deakin University.

Sourcing material parts in order to achieve unusual properties of a metamaterial can be time consuming and expensive. This new way of thinking about the design of metamaterials may allow researchers to produce the optical properties they want from the metamaterial using only two component parts.

“What this [research] really does is put a new spin on the idea that with only two set materials arranged with the right portions – one metal, one insulator, here silver and silica – almost any optical property can be achieved,” said Associate Professor Kuhlmey.

Professor Walsh said: “This is like the concept of turning sound waves from analog into digital – and they’ve pushed it into a new realm of physics.

“They’ve been able to take the permittivity – the response of the material when it’s exposed to radiation – and digitised this. They’ve turned it into something that is more readily manipulated.”
Waves and matter collide

One of the key applications for metamaterials lies in their ability to manipulate light.

“We already have knowledge about how to manipulate radiation (such as light) – we can use lenses, like a magnifying glass, for example, which focus light down on a spot; we can use mirrors to reflect light and change its direction,” Professor Walsh said.

“But what these [metamaterials] can do is something more sophisticated: they’re able to bend light, to scatter it, to manipulate it in unusual ways.”

Using their digital method, the researchers showed that it is possible to create certain metamaterials with very low permittivity, which are rarely found in nature. Having control over these properties may open doors to more advanced technological applications, such as invisibility cloaking devices.

“It would be interesting in future to see if such a digital design method can facilitate the construction of optical, or invisibility, cloaks,“ said Professor Gu.

“With varying changes of silver/glass ratios (structured at the nanoscale) it is then in principle possible to make flat lenses and other tiny optical elements,” Associate Professor Kuhlmey said.

“The authors […] showed in simulations that nano-patterned glass/silver structures can then bend light, which is also the principle behind invisibility cloaking.”

He added that fabricating the proposed structures would be challenging but not impossible.

“[It would] require structuring glass and metal with a precision of a few atoms in thickness only – but thinking of metamaterials as binary structures may help devise new nano-patterning lithography (printing) techniques that take advantage of this,” he said.

NASA MAVEN Spacecraft Prepares for Mars Orbit-Insertion Maneuver

This artist concept depicts the process of orbital insertion of NASA’s Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft. Image Credit: NASA/GSFC

Launched last November, the MAVEN spacecraft is now preparing for an orbit-insertion maneuver that will allow the spacecraft to be pulled into an elliptical orbit of Mars with a period of 35 hours.

NASA’s Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft is nearing its scheduled September 21 insertion into Martian orbit after completing a 10-month interplanetary journey of 442 million miles.

Flight Controllers at Lockheed Martin Space Systems in Littleton, Colorado, will be responsible for the health and safety of the spacecraft throughout the process. The spacecraft’s mission timeline will place the spacecraft in orbit at approximately 9:50 p.m. EDT.

“So far, so good with the performance of the spacecraft and payloads on the cruise to Mars,” said David Mitchell, MAVEN project manager at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “The team, the flight system, and all ground assets are ready for Mars orbit insertion.”

The orbit-insertion maneuver will begin with the brief firing of six small thruster engines to steady the spacecraft. The engines will ignite and burn for 33 minutes to slow the craft, allowing it to be pulled into an elliptical orbit with a period of 35 hours.

Following orbit insertion, MAVEN will begin a six-week commissioning phase that includes maneuvering the spacecraft into its final orbit and testing its instruments and science-mapping commands. Thereafter, MAVEN will begin its one-Earth-year primary mission to take measurements of the composition, structure and escape of gases in Mars’ upper atmosphere and its interaction with the sun and solar wind.

“The MAVEN science mission focuses on answering questions about where did the water that was present on early Mars go, about where did the carbon dioxide go,” said Bruce Jakosky, MAVEN principal investigator from the University of Colorado, Boulder’s Laboratory for Atmospheric and Space Physics. “These are important questions for understanding the history of Mars, its climate, and its potential to support at least microbial life.”

MAVEN launched November 18, 2013, from Cape Canaveral, Florida, carrying three instrument packages. It is the first spacecraft dedicated to exploring the upper atmosphere of Mars. The mission’s combination of detailed measurements at specific points in Mars’ atmosphere and global imaging provides a powerful tool for understanding the properties of the Red Planet’s upper atmosphere.

“MAVEN is another NASA robotic scientific explorer that is paving the way for our journey to Mars,” said Jim Green, director of the Planetary Science Division at NASA Headquarters in Washington. “Together, robotics and humans will pioneer the Red Planet and the solar system to help answer some of humanity’s fundamental questions about life beyond Earth.”

The spacecraft’s principal investigator is based at the Laboratory for Atmospheric and Space Physics at University of Colorado, Boulder. The university provided two science instruments and leads science operations, as well as education and public outreach, for the mission.

NASA Goddard Space Flight Center in Greenbelt, Maryland, manages the project and also provided two science instruments for the mission. Lockheed Martin built the spacecraft and is responsible for mission operations. The Space Sciences Laboratory at the University of California at Berkeley provided four science instruments for MAVEN. NASA’s Jet Propulsion Laboratory in Pasadena, California, provides navigation and Deep Space Network support, and Electra telecommunications relay hardware and operations.

Programmable Biofilm-Based Materials That Self-Assemble

Biofilms are communities of bacteria ensconced in a matrix of slimy, but extremely tough, extracellular material composed of sugars, proteins, genetic material, and more. Associate Professor of Chemical and Biological Engineering Neel Joshi and his team wanted to give them a facelift, and developed a novel protein-engineering system called BIND to do so.

A newly published study details how researchers at Wyss Institute for Biologically Inspired Engineering at Harvard University are using biofilms to create self-healing materials and other technologies.

For many people, biofilms conjure up images of slippery stones in streambeds or dirty drains. A team at the Wyss Institute for Biologically Inspired Engineering at Harvard University thinks of them instead as a robust new platform for designer nanomaterials that could help clean polluted rivers, manufacture pharmaceutical products, fabricate new textiles, and more.

Biofilms are communities of bacteria ensconced in a matrix of slimy, but extremely tough, extracellular material composed of sugars, proteins, genetic material, and more. Researchers wanted to give them a facelift, and developed a novel protein-engineering system called BIND to do so. With BIND, which stands for biofilm-integrated nanofiber display, the team said biofilms could become living foundries for large-scale production of biomaterials that can be programmed to provide functions not possible with existing materials. They reported the proof-of-concept today in the journal Nature Communications.

“Most biofilm-related research today focuses on how to get rid of biofilms, but we demonstrate here that we can engineer these super-tough natural materials to perform specific functions, so we may want them around in specific quantities and for specific applications,” said Wyss Institute Core Faculty member Neel Joshi, the study’s senior author. Joshi is also an associate professor of chemical and biological engineering at the Harvard School of Engineering and Applied Sciences (SEAS).

Biofilms also can self-assemble and self-heal. “If they get damaged, they grow right back because they are living tissues,” said lead author Peter Nguyen, a postdoctoral fellow at the Wyss Institute and SEAS.

During biofilm formation, individual bacteria pump out proteins that self-assemble outside the cell, creating tangled networks of fibers that essentially glue the cells together into communities that keep the bacteria safer than they would be on their own.

Interest in biofilm engineering is skyrocketing, and while several other teams have recently developed genetic tools to control biofilm formation, Joshi’s team altered the composition of the extracellular material itself, essentially turning it into a self-replicating production platform to churn out whatever material they wish to produce.

“Until recently, there was not enough cooperation between synthetic biologists and biomaterials researchers to exploit the synthetic potential of biofilms this way. We are trying to bridge that gap,” Joshi said.

The team genetically fuse a protein with a particular desired function — for example, one known to adhere to steel — onto a small protein called CsgA that is already produced by E. coli bacteria. The appended domain goes along for the ride through the natural process by which CsgA is secreted outside the cell, where it self-assembles into super-tough proteins called amyloid nanofibers. These amyloid proteins retain the functionality of the added protein, ensuring the desired function, in this case that the biofilm adheres to steel.

Amyloid proteins traditionally get a bad rap for their role in causing tremendous health challenges such as Alzheimer’s disease, but here their role is fundamental to making BIND robust. The amyloids can spontaneously assemble into fibers that, by weight, are stronger than steel and stiffer than silk.

“We are excited about the versatility of the method, too,” Joshi said. The team demonstrated an ability to fuse 12 different proteins to the CsgA protein, with widely varying sequences and lengths. This means that in principle they can use this technology to display virtually any protein sequence — a significant feature because proteins perform an array of impressive functions, from binding to foreign particles, to carrying out chemical reactions, to transmitting signals, providing structural support, and transporting or storing certain molecules.

Not only can these functions be programmed into the biofilm one at a time, they can be combined to create multifunctional biofilms as well.

The concept of the microbial factory is not a new one, but this is the first time it is being applied to materials, as opposed to soluble molecules such as drugs or fuels. “We are essentially programming the cells to be fabrication plants,” Joshi said. “They don’t just produce a raw material as a building block, they orchestrate the assembly of those blocks into higher-order structures and maintain those structures over time.”

“The foundational work Neel and his team are doing with biofilms offers a glimpse into a much more environmentally sustainable future, where gargantuan factories are reduced to the size of a cell that we can program to manufacture new materials that meet our everyday needs — from textiles to energy and environmental clean-up,” said Wyss Institute Founding Director Don Ingber.

For now, the team has demonstrated the ability to program E. coli biofilms that stick to certain substrates such as steel, and others that can immobilize an array of proteins or promote the templating of silver for construction of nanowires.

This work was primarily funded by the Wyss Institute. The authors also acknowledge support from the National Science Foundation Graduate Research Fellowship and the A*STAR National Science Graduate Fellowship.

Graphene Nanoribbon Film Keeps Glass Ice-Free

Rice University’s high-density graphene nanoribbon film are fabricated in a multistep process. Credit: J.M. Tour/Rice University

Researchers from Rice University have developed a transparent graphene nanoribbon film that can be used to prevent ice and fog buildup on glass and plastic, as well as radar domes and antennas.

Rice University scientists who created a de-icing film for radar domes have now refined the technology to work as a transparent coating for glass.

The new work by Rice chemist James Tour and his colleagues could keep glass surfaces from windshields to skyscrapers free of ice and fog while retaining their transparency to radio frequencies (RF).

The technology was introduced this month in the American Chemical Society journal Applied Materials and Interfaces.

The material is made of graphene nanoribbons, atom-thick strips of carbon created by splitting nanotubes, a process also invented by the Tour lab. Whether sprayed, painted or spin-coated, the ribbons are transparent and conduct both heat and electricity.

Last year the Rice group created films of overlapping nanoribbons and polyurethane paint to melt ice on sensitive military radar domes, which need to be kept clear of ice to keep them at peak performance. The material would replace a bulky and energy-hungry metal oxide framework.

The graphene-infused paint worked well, Tour said, but where it was thickest, it would break down when exposed to high-powered radio signals. “At extremely high RF, the thicker portions were absorbing the signal,” he said. “That caused degradation of the film. Those spots got so hot that they burned up.”

This scanning electron microscope image shows a closeup of nanoribbon network in Rice University’s high-density graphene nanoribbon film. Credit: A.O. Raji/Rice University

The answer was to make the films more consistent. The new films are between 50 and 200 nanometers thick – a human hair is about 50,000 nanometers thick – and retain their ability to heat when a voltage is applied. The researchers were also able to preserve their transparency. The films are still useful for de-icing applications but can be used to coat glass and plastic as well as radar domes and antennas.

In the previous process, the nanoribbons were mixed with polyurethane, but testing showed the graphene nanoribbons themselves formed an active network when applied directly to a surface. They were subsequently coated with a thin layer of polyurethane for protection. Samples were spread onto glass slides that were then iced. When voltage was applied to either side of the slide, the ice melted within minutes even when kept in a minus-20-degree Celsius environment, the researchers reported.

“One can now think of using these films in automobile glass as an invisible de-icer, and even in skyscrapers,” Tour said. “Glass skyscrapers could be kept free of fog and ice, but also be transparent to radio frequencies. It’s really frustrating these days to find yourself in a building where your cellphone doesn’t work. This could help alleviate that problem.”

Tour noted future generations of long-range Wi-Fi may also benefit. “It’s going to be important, as Wi-Fi becomes more ubiquitous, especially in cities. Signals can’t get through anything that’s metallic in nature, but these layers are so thin they won’t have any trouble penetrating.”

He said nanoribbon films also open a path toward embedding electronic circuits in glass that are both optically and RF transparent.

Rice graduate student Abdul-Rahman Raji is lead author of the paper. Co-authors are Rice graduate student Errol Samuel and researcher Sydney Salters, a student at Second Baptist School, Houston; Rice alumnus Yu Zhu, now an assistant professor at the University of Akron, Ohio; and Vladimir Volman, an engineer at Lockheed Martin. Tour is the T.T. and W.F. Chao Chair in Chemistry as well as a professor of materials science and nanoengineering and of computer science. He is a member of the Richard E. Smalley Institute for Nanoscale Science and Technology.

The Lockheed Martin Aerospace Co. through the LANCER IV Program, the Office of Naval Research’s Multidisciplinary University Research Initiative and the Air Force Office of Scientific Research supported the research.

Publication: Abdul-Rahman O. Raji, et al., “Functionalized Graphene Nanoribbon Films as a Radiofrequency and Optically Transparent Material,” ACS Appl. Mater. Interfaces, 2014; DOI: 10.1021/am503478w

New Model Reveals Spreading Continents Kick-Started Plate Tectonics

A snapshot from the film after 45 million years of spreading. The pink is the region where the mantle underneath the early continent has melted, facilitating its spreading, and the initiation of the plate tectonic process. Credit: Patrice Rey, Nicolas Flament and Nicolas Coltice

New research from the University of Sydney is shedding light on what set the Earth’s massive tectonic plates in motion, suggesting that it was triggered by the spreading of the early continents and eventually it became a self-sustaining process.

The mystery of what kick-started the motion of our earth’s massive tectonic plates across its surface has been explained by researchers at the University of Sydney.

“Earth is the only planet in our solar system where the process of plate tectonics occurs,” said Associate Professor Patrice Rey, from the University of Sydney’s School of Geosciences.

“The geological record suggests that until three billion years ago the earth’s crust was immobile so what sparked this unique phenomenon has fascinated geoscientists for decades. We suggest it was triggered by the spreading of early continents then eventually became a self-sustaining process.”

Associate Professor Rey is lead author of an article on the findings published in Nature today.

The other authors on the paper are Dr Nicolas Flament, also from the School of Geosciences and Professor Nicolas Coltice, from the University of Lyon.

There are eight major tectonic plates that move above the earth’s mantle at rates up to 150 millimeters every year.

In simple terms the process involves plates being dragged into the mantle at certain points and moving away from each other at others, in what has been dubbed ‘the conveyor belt’.

Plate tectonics depends on the inverse relationship between density of rocks and temperature.

An 87 million year long story. This shows an early buoyant continent slowly spreading toward the adjacent immobile plate (blue). After 45 million years, a short-lived subduction zone, where the plate goes under, develops. This allows the continent to surge toward the ocean, leading to the detachment of a continental block, the starting step in the movement of the continental plates.

At mid-oceanic ridges, rocks are hot and their density is low, making them buoyant or more able to float. As they move away from those ridges they cool down and their density increases until, where they become denser than the underlying hot mantle, they sink and are ‘dragged’ under.

But three to four billion years ago, the earth’s interior was hotter, volcanic activity was more prominent and tectonic plates did not become cold and dense enough to spontaneously sank.

“So the driving engine for plate tectonics didn’t exist,” said Professor Rey said.

“Instead, thick and buoyant early continents erupted in the middle of immobile plates. Our modelling shows that these early continents could have placed major stress on the surrounding plates. Because they were buoyant they spread horizontally, forcing adjacent plates to be pushed under at their edges.”

“This spreading of the early continents could have produced intermittent episodes of plate tectonics until, as the earth’s interior cooled and its crust and plate mantle became heavier, plate tectonics became a self-sustaining process which has never ceased and has shaped the face of our modern planet.”

The new model also makes a number of predictions explaining features that have long puzzled the geoscience community.

Publication: Patrice F. Rey, et al., “Spreading continents kick-started plate tectonics,” Nature 513, 405–408 (18 September 2014); doi:10.1038/nature13728

The First Truly Semiaquatic Dinosaur, Spinosaurus Aegyptiacus

The only known dinosaur adapted to life in water, Spinosaurus swam the rivers of North Africa a hundred million years ago. The massive Cretaceous predator lived in a region mostly devoid of large, terrestrial plant-eaters, subsisting mainly on huge fish. Illustration by Davide Bonadonna

An international team of scientists has unveiled the first truly semiaquatic dinosaur, Spinosaurus aegyptiacus. New fossils of the massive Cretaceous-era predator reveal it adapted to life in the water some 95 million years ago, providing the most compelling evidence to date of a dinosaur able to live and hunt in an aquatic environment.

The fossils also indicate that Spinosaurus was the largest known predatory dinosaur to roam the Earth, measuring more than nine feet longer than the world’s largest Tyrannosaurus rex specimen. These findings, published online on the Science Express website, also are featured in the October National Geographic magazine cover story.

An international research team—including paleontologists Nizar Ibrahim and Paul Sereno from the University of Chicago; Cristiano Dal Sasso and Simone Maganuco from the Natural History Museum in Milan, Italy; and Samir Zouhri from the Université Hassan II Casablanca in Morocco—found that Spinosaurus developed a variety of previously unknown aquatic adaptations. The researchers came to their conclusions after analyzing new fossils uncovered in the Moroccan Sahara and a partial Spinosaurus skull and other remains housed in museum collections around the world. They also used historical records and images from the first reported Spinosaurus discovery in Egypt more than 100 years ago. According to lead author Ibrahim, a 2014 National Geographic Emerging Explorer, “Working on this animal was like studying an alien from outer space; it’s unlike any other dinosaur I have ever seen.”

An international research team—including paleontologists Nizar Ibrahim and Paul Sereno from the University of Chicago; Cristiano Dal Sasso and Simone Maganuco from the Natural History Museum in Milan, Italy; and Samir Zouhri from the Université Hassan II Casablanca in Morocco—found that Spinosaurus developed a variety of previously unknown aquatic adaptations. The researchers came to their conclusions after analyzing new fossils uncovered in the Moroccan Sahara and a partialSpinosaurus skull and other remains housed in museum collections around the world. They also used historical records and images from the first reported Spinosaurusdiscovery in Egypt more than 100 years ago. According to lead author Ibrahim, a 2014 National Geographic Emerging Explorer, “Working on this animal was like studying an alien from outer space; it’s unlike any other dinosaur I have ever seen.”

An international research team worked on Spinosaurus, including Nizar Ibrahim (left), a UChicago postdoctoral scholar, and Prof. Paul Sereno. Photo by Mike Hettwer

Aquatic adaptations of Spinosaurus

The aquatic adaptations of Spinosaurus differ significantly from earlier members of the spinosaurid family that lived on land but were known to eat fish. These adaptations include:

• Small nostrils located in the middle of the skull. The small size and placement of the nostrils farther back on the skull allowed Spinosaurus to breathe when part of its head was in water.
• Neurovascular openings at the end of the snout. Similar openings on crocodile and alligator snouts contain pressure receptors that enable them to sense movement in water. It’s likely these openings served a comparable function in Spinosaurus.
• Giant, slanted teeth that interlocked at the front of the snout. The conical shape and location of the teeth were well-suited for catching fish.
• A long neck and trunk that shifted the dinosaur’s center of mass forward. This made walking on two legs on land nearly impossible, but facilitated movement in water.
• Powerful forelimbs with curved, blade-like claws. These claws were ideal for hooking or slicing slippery prey.
• A small pelvis and short hind legs with muscular thighs. As in the earliest whales, these adaptations were for paddling in water and differ markedly from other predatory dinosaurs that used two legs to move on land.
• Particularly dense bones lacking the marrow cavities typical to predatory dinosaurs. Similar adaptations, which enable buoyancy control, are seen in modern aquatic animals like king penguins.
• Strong, long-boned feet and long, flat claws. Unlike other predators,Spinosaurus had feet similar to some shorebirds that stand on or move across soft surfaces rather than perch. In fact, Spinosaurus may have had webbed feet for walking on soft mud or paddling.
• Loosely connected bones in the dinosaur’s tail. These bones enabled its tail to bend in a wave-like fashion, similar to tails that help propel some bony fish.
• Enormous dorsal spines covered in skin that created a gigantic “sail” on the dinosaur’s back. The tall, thin, blade-shaped spines were anchored by muscles and composed of dense bone with few blood vessels. This suggests the sail was meant for display and not to trap heat or store fat. The sail would have been visible even when the animal entered the water.

Discovery more than century in making

More than a century ago, German paleontologist Ernst Freiherr Stromer von Reichenbach first discovered evidence of Spinosaurus in the Egyptian Sahara. Sadly, all of Stromer’s fossils were destroyed during the April 1944 Allied bombing of Munich, Germany. Ibrahim, however, was able to track down Stromer’s surviving notes, sketches and photos in archives and at the Stromer family castle in Bavaria to supplement Stromer’s surviving publications.

The new Spinosaurus fossils were discovered in the Moroccan Sahara along desert cliffs known as the Kem Kem beds. This area was once a large river system, stretching from present-day Morocco to Egypt. At the time, a variety of aquatic life populated the system, including large sharks, coelacanths, lungfish and crocodile-like creatures, along with giant flying reptiles and predatory dinosaurs.

The most important of the new fossils, a partial skeleton uncovered by a local fossil hunter, was spirited out of the country. As a result, critical information about the context of the find was seemingly lost, and locating the local fossil hunter in Morocco was nearly impossible. Remarked Ibrahim, “It was like searching for a needle in a desert.” After an exhaustive search, Ibrahim finally found the man and confirmed the site of his original discovery.

To unlock the mysteries of Spinosaurus, the team created a digital model of the skeleton with funding provided by the National Geographic Society. The researchers CT scanned all of the new fossils, which will be repatriated to Morocco, complementing them with digital recreations of Stromer’s specimens. Missing bones were modeled based on known elements of related dinosaurs. According to Maganuco, “We relied upon cutting-edge technology to examine, analyze and piece together a variety of fossils. For a project of this complexity, traditional methods wouldn’t have been nearly as accurate.”

The researchers then used the digital model to create an anatomically precise, life-size 3-D replica of the Spinosaurus skeleton. After it was mounted, the researchers measured Spinosaurus from head to tail, confirming their calculation that the new skeleton was longer than the largest documented Tyrannosaurus by more than nine feet. According to Sereno, head of the University of Chicago’s Fossil Lab, “What surprised us even more than the dinosaur’s size were its unusual proportions. We see limb proportions like this in early whales, not predatory dinosaurs.”

Added Dal Sasso, “In the last two decades, several finds demonstrated that certain dinosaurs gave origins to birds. Spinosaurus represents an equally bizarre evolutionary process, revealing that predatory dinosaurs adapted to a semiaquatic life and invaded river systems in Cretaceous North Africa.”

Other authors of the Science paper are David Martill, University of Portsmouth, United Kingdom; Matteo Fabbri, University of Bristol, United Kingdom; Nathan Myhrvold, Intellectual Ventures; and Dawid Iurino, Sapienza Università di Roma in Italy. Important contributors to the making of the digital Spinosaurus include Tyler Keillor, Lauren Conroy and Erin Fitzgerald of the Fossil Lab at the University of Chicago.

Publication: Nizar Ibrahim, et al., “Semiaquatic adaptations in a giant predatory dinosaur,” Science, 2014; DOI: 10.1126/science.1258750

Zebrafish Larva Eye Distinguishes Between Prey and Predator

Small and large objects activate various circuits in the visual system of zebrafish larvae. This separation begins in the eye and probably decides the direction of the swimming behavior. Credit: Max Planck Institute for Medical Research

A new study from the Max Planck Institute for Medical Research reveals how the eye of a zebrafish larva can already distinguish between prey and predator.

Red or green? Small or large? Fast or slow? Humans and animals rely on their visual organs to classify objects in their environment. Decisions about how we best respond to moving objects in our environment are often made very quickly and unconsciously. The size of a moving object is obviously an important criterion. The rapid speed of a response suggests that specialized neural circuits in the visual system are responsible for recognizing important object properties. If they are activated, they trigger the “fight” or “flight” signal in the brain. Scientists at the Max Planck Institute for Medical Research in Heidelberg have now shed light on how such circuits, which are likely to be crucial in classifying objects by size, function in the brain of the zebrafish larva.

How does the brain decide which things in our complex environment require an immediate response from us? A key question in the animal kingdom is: “Is the object moving in my environment prey or predator?” – a question that requires a quick answer in an emergency. Evidently, the visual system manages to detect objects from the constantly changing distribution of light stimuli on the retina based on simple criteria and, if necessary, mobilize a rapid response directly. The basic mechanisms of object classification can be studied using zebrafish larva as the model system.

The larva’s well-developed visual system allows it to catch small prey and avoid larger objects. The decision about whether the larva approaches or avoids the object is made on the basis of size. Researchers working with Johann Bollmann at the Max Planck Institute in Heidelberg have now been able to demonstrate that small and large stimuli, which trigger swimming movements in different directions, generate neural activity in neighboring but different circuits in the fish’s brain. The behavior-related distinction in size thus begins in the ganglion cells of the eye.

The retina in the eye contains a variety of different ganglion cells which respond specifically to color, size, movement or contrast, for example. However, little is understood about how these different messages travel via the optic nerve to the brain and are processed. The researchers were now able to identify such cells in a central area of the fish’s brain – the tectum. These cells respond specifically to those object sizes that correspond to a small prey or a large troublemaker in the world of the zebrafish larva.

It turns out that the nerve endings of ganglion cells, which project into the tectum, respond differently to object size. Other cell types downstream in the tectum distinguish between small and large objects on the zebrafish’s magnitude scale in their activity patterns, depending on the layer in which they receive their synaptic inputs.

“This suggests that the size classification process begins in the retina of the eye to subsequently classify the object that is seen in the tectum into the categories of ‘small enough to count as prey’ or ‘sufficiently large to watch out for’. The fish larva then adapts its behavior accordingly,” says Johann Bollmann from the Max Planck Institute for Medical Research. The brains of mammals contain very similar structures that are crucially involved in the visual control of such targeted movements. This suggests that the functions of detecting objects and controlling actions are resolved in a similar way as they are in the small brain of the fish larva.

Publication: Stephanie J. Preuss, et al., “Classification of Object Size in Retinotectal Microcircuits,” Current Biology, 19 September 2014; DOI: 10.1016/j.cub.2014.09.012