Scottish Scientists Slow down Light Particles - Photons

The speed of light is a limit, not a constant, that's what researchers in Glasgow, Scotland, say. A group of them just proved that light can be slowed down, permanently.

Scientists already knew light could be slowed temporarily. Photons change speeds as they pass through glass or water, but when they exit the other side and return to a vacuum (like outer space) they speed back up.

In a new experiment at the University of Glasgow, however, scientists were able to permanently manipulate light's speed by passing photons through a device that alters their structure. The device, created in collaboration with researchers at Heriot-Watt University in Edinburgh, is a filter of sorts that the scientists refer to as a mask.

"That mask looks a little bit like a bull's-eye target," researcher Miles Padgett told reporters. "And that mask patterns the light beam, and we show that it's the patterning of the light beam that slows it down.

"But once that pattern has been imposed, even now the light is no longer in the mask, it's just propagating in free space, the speed is still slow," Padgett added.

In other words, the beam of light is reorganized in a way that slows down each individual photon. When tested in a vacuum next to a regular light beam.

Photons that had been filtered through mask were milliseconds behind in a sprint to the end of the vacuum racetrack.

Researchers, whose latest work was published this week in the journal Science Express, say the findings prove the speed of light is not an absolute, more like a ceiling.

Miles Padgett

The work was carried out by a team from the University of Glasgow’s Optics Group, led by Professor Miles Padgett, working with theoretical physicists led by Stephen Barnett, in partnership with Professor Daniele Faccio from Heriot-Watt’s Institute of Photonics and Quantum Sciences.

Daniele Faccio

Professor Faccio said, “The speed of light is a universal constant and plays a central role in our understanding of the Universe and Einstein's theory of relativity."

"The exciting discovery here is that this speed is the true speed of light only for plane waves, that is waves that are perfectly flat."

"In everyday situations however, we interact with light that is not a plane wave but has some kind of structure on it."

"The presence of this structure (think of the light beam emitted from a laser pointer) forces the light to actually move slower."

"There are lots of technicalities involved in the actual experiments used to measure this slow-down, but the result is widely applicable. A very appropriate discovery for the 2015 international year of light".

Professor Padgett added, “It might seem surprising that light can be made to travel more slowly like this, but the effect has a solid theoretical foundation and we’re confident that our observations are correct.

“The results give us a new way to think about the properties of light and we’re keen to continue exploring the potential of this discovery in future applications."

"We expect that the effect will be applicable to any wave theory, so a similar slowing could well be created in sound waves, for example.”

More Information
Spatially structured photons that travel in free space slower than the speed of light - Science Magazine January 22 2015 - Science DOI: 10.1126/science.aaa3035

NASA SDO: Largest Sunspot in 24 Years Mystifies Scientists

The Jupiter-sized sunspot AR 12192 is the largest active region seen on the sun in 24 years. 

Credit: NASA SDO

The biggest sunspot to grace the face of the sun in more than two decades just rotated out of Earth's view, but it was responsible for kicking up some truly amazing solar activity this week.

The sunspot (called Active Region 12192 or AR 2192) shot off four powerful flares in four days recently, with many more smaller flares sprinkled in as well.

The sunspot region was about the size of the planet Jupiter and is the largest solar flare observed in 24 years.

AR 2192 was actually one of the biggest observed sunspots of all time, ranking 33rd largest of 32,908 active regions since 1874, according to NASA scientists C. Alex Young and Dean Pesnell. But how does a sunspot grow this big?

"The simple answer is we really don't know," Young told reporters.

"Being close to solar maximum [the peak in the sun's 11-year solar cycle] means there is more concentrated magnetic field and magnetic energy under the solar surface waiting to bubble up, but the question of why it comes up as one spot instead of two or more is really still unknown, a mystery."

"I guess a good analogy is when you twist a rubber band or piece of string," Young added. "Why do, say, three knots or bunches form instead of two or four?"

"The physics is probably too complicated for us at this point but we can get a handle on, say, when the knots will start to form once we better understand the properties of the rubber band or string and how much twist we put into them. We are not to that point with the sun but we may get there eventually."

The largest sunspot since November 1990 is seen traveling across the front of the sun in these images from NASA's SDO, captured Oct. 17-Oct 29, 2014.

Image Credit: NASA/SDO

Sunspots are active areas on the sun. They generally form when magnetic field lines are warped, and if they become twisted.

Part of it may break out, and show up on the face of the star. Sunspots look dark because they are cooler than the area surrounding them.

This sunspot is particularly special because of the somewhat strange way scientists have seen it behave.



Instead of shooting out huge bursts of plasma, called coronal mass ejections (CMEs), with powerful flares, the giant sunspot hasn't produced significant CMEs during its time rotating in view of Earth, according to Young.

"What's really curious about it [the large sunspot] is that it's produced so many flares of pretty good size, but little or no coronal mass ejections," Young said.

"It's not that it's never happened before, but it tends to be the case that when you have a big flare, you generally get a big CME."

Earth-directed CMEs are responsible for geomagnetic storms that can harm satellites in orbit or even knock out power grids on the planet.

A CME produced by a sunspot larger than AR 2192 knocked out the power in Quebec, Canada, in 1989, Young said.

The sunspot just rotated out of view of Earth, according to Spaceweather.com, but that doesn't necessarily mean that AR 2192 won't make another appearance on Earth's side of the star.

Scientists build first 3D map of hidden universe

3D map of the cosmic web at a distance of 10.8 billion light years from Earth. 

The map was generated from imprints of hydrogen gas observed in the spectrum of 24 background galaxies, which are located behind the volume being mapped. 

This is the first time that large-scale structures in such a distant part of the Universe have been mapped directly. 

The colouring represents the density of hydrogen gas tracing the cosmic web, with brighter colors representing higher density. 

Credit: Casey Stark (UC Berkeley) and Khee-gan Lee (MPIA)

A team led by astronomers from the Max Planck Institute for Astronomy has created the first three-dimensional map of the 'adolescent' Universe, just 3 billion years after the Big Bang.

This map, built from data collected from the W. M. Keck Observatory, is millions of light-years across and provides a tantalizing glimpse of large structures in the 'cosmic web', the backbone of cosmic structure.

On the largest scales, matter in the Universe is arranged in a vast network of filamentary structures known as the 'cosmic web', its tangled strands spanning hundreds of millions of light-years.

Dark matter, which emits no light, forms the backbone of this web, which is also suffused with primordial hydrogen gas left over from the Big Bang.

Galaxies like our own Milky Way are embedded inside this web, but fill only a tiny fraction of its volume.

Now a team of astronomers led by Khee-gan Lee, a post-doc at the Max Planck Institute for Astronomy, has created a map of hydrogen absorption revealing a three-dimensional section of the universe 11 billions light years away, the first time the cosmic web has been mapped at such a vast distance.

Since observing to such immense distances is also looking back in time, the map reveals the early stages of cosmic structure formation when the Universe was only a quarter of its current age, during an era when the galaxies were undergoing a major 'growth spurt'.

The map was created by using faint background galaxies as light sources, against which gas could be seen by the characteristic absorption features of hydrogen.

The wavelengths of each hydrogen feature showed the presence of gas at a specific distance from us.

Combining all of the measurements across the entire field of view allowed the team a tantalizing glimpse of giant filamentary structures extending across millions of light-years, and paves the way for more extensive studies that will reveal not only the structure of the cosmic web, but also details of its function, the ways that pristine gas is funneled along the web into galaxies, providing the raw material for the formation of galaxies, stars, and planets.

Credit: Casey Stark (UC Berkeley) And Khee-gan Lee (MPIA)

Using the light from faint background galaxies for this purpose had been thought impossible with current telescopes, until Lee carried out calculations that suggested otherwise.

To ensure success, Lee and his colleagues obtained observing time at Keck Observatory, home of the two largest and most scientifically productive telescopes in the world.

Although bad weather limited the astronomers to observing for only 4 hours, the data they collected with the LRIS instrument was completely unprecedented.

"We were pretty disappointed as the weather was terrible and we only managed to collect a few hours of good data, but judging by the data quality as it came off the telescope, it was clear to me that the experiment was going to work," said Max Plank's Joseph Hennawi, who was part of the observing team.

"The data were obtained using the LRIS spectrograph on the Keck I telescope," Lee said.

"With its gargantuan 10m-diameter mirror, this telescope effectively collected enough light from our targeted galaxies that are more than 15 billion times fainter than the faintest stars visible to the naked eye."

"Since we were measuring the dimming of blue light from these distant galaxies caused by the foreground gas, the thin atmosphere at the summit of Mauna Kea allowed more of this blue light to reach the telescope and be measured by the highly sensitive detectors of the LRIS spectrograph."

"The data we collected would have taken at least several times longer to obtain on any other telescope."

Their absorption measurements using 24 faint background galaxies provided sufficient coverage of a small patch of the sky to be combined into a 3D map of the foreground cosmic web.

A crucial element was the computer algorithm used to create the 3D map: due to the large amount of data, a naïve implementation of the map-making procedure would require an inordinate amount of computing time.

Casey Stark

Fortunately, team members Casey Stark and Martin White (UC Berkeley and Lawrence Berkeley National Lab) devised a new fast algorithm that could create the map within minutes.

"We realized we could simplify the computations by tailoring it to this particular problem, and thus use much less memory. A calculation that previously required a supercomputer now runs on a laptop", says Stark.

The resulting map of hydrogen absorption reveals a three-dimensional section of the universe 11 billions light years away, this is first time the cosmic web has been mapped at such a vast distance.

Since observing to such immense distances is also looking back in time, the map reveals the early stages of cosmic structure formation when the Universe was only a quarter of its current age, during an era when the galaxies were undergoing a major 'growth spurt'.

The map provides a tantalizing glimpse of giant filamentary structures extending across millions of light-years, and paves the way for more extensive studies that will reveal not only the structure of the cosmic web, but also details of its function, the ways that pristine gas is funneled along the web into galaxies, providing the raw material for the formation of galaxies, stars, and planets.

Scientists New Estimate of Dark Matter Half previous estimate

Artist’s impression of the Milky Way and its dark matter halo (shown in blue, but in reality invisible). 

Credit: ESO/L. Calçada

A new measurement of dark matter in the Milky Way has revealed there is half as much of the mysterious substance as previously thought.

Australian astronomers used a method developed almost 100 years ago to discover that the weight of dark matter in our own galaxy is 800 000 000 000 (or 8 x 1011) times the mass of the Sun.

They probed the edge of the Milky Way, looking closely, for the first time, at the fringes of the galaxy about 5 million billion kilometres from Earth.

Astrophysicist Dr Prajwal Kafle, from The University of Western Australia node of the International Centre for Radio Astronomy Research (ICRAR), said we have known for a while that most of the Universe is hidden.

"Stars, dust, you and me, all the things that we see, only make up about 4 per cent of the entire Universe," he said.

"About 25 per cent is dark matter and the rest is dark energy."

Dr Kafle, who is originally from Nepal, was able to measure the mass of the dark matter in the Milky Way by studying the speed of stars throughout the galaxy, including the edges, which had never been studied to this detail before.

He used a robust technique developed by British astronomer James Jeans in 1915, decades before the discovery of dark matter.

Dr Kafle's measurement helps to solve a mystery that has been haunting theorists for almost two decades.

"The current idea of galaxy formation and evolution, called the Lambda Cold Dark Matter theory, predicts that there should be a handful of big satellite galaxies around the Milky Way that are visible with the naked eye, but we don't see that," Dr Kafle said.



"When you use our measurement of the mass of the dark matter the theory predicts that there should only be three satellite galaxies out there, which is exactly what we see; the Large Magellanic Cloud, the Small Magellanic Cloud and the Sagittarius Dwarf Galaxy."

University of Sydney astrophysicist Professor Geraint Lewis, who was also involved in the research, said the missing satellite problem had been "a thorn in the cosmological side for almost 15 years."

"Dr Kafle's work has shown that it might not be as bad as everyone thought, although there are still problems to overcome," he said.

The study also presented a holistic model of the Milky Way, which allowed the scientists to measure several interesting things such as the speed required to leave the galaxy.

"Be prepared to hit 550 kilometres per second if you want to escape the gravitational clutches of our galaxy," Dr Kafle said.

"A rocket launched from Earth needs just 11 kilometres per second to leave its surface, which is already about 300 times faster than the maximum Australian speed limit in a car!"

More information: 'On the Shoulders of Giants: Properties of the Stellar Halo and the Milky Way Mass Distribution' P. R. Kafle, S. Sharma, G. F. Lewis, and J. Bland-Hawthorn. Published in the Astrophysical Journal October 10th, 2014. Available at: iopscience.iop.org/0004-637X/794/1/59/. arxiv.org/abs/1408.1787

Deviation in satellite flybys: An anomaly that confounds scientists

An artist's rendition of Rosetta probe during a flyby. 

Credit: ESA/C.Carreau

When space probes, such as ESA's Rosetta and NASA's Cassini, fly over certain planets and moons in order to gain momentum and travel long distances, their speed changes slightly for an unknown reason.

A Spanish researcher has now analysed whether or not a hypothetical gravitomagnetic field could have an influence.

However, other factors such as solar radiation, tides, or even relativistic effects or dark matter could be behind this mystery.

Since the beginnings of space exploration, many spacecraft have gone into a hyperbolic orbit around planets or moons, with the aim of taking advantage of their gravitational energy and go toward their target.

However, during this flyby manoeuvre, something makes the spacecraft speed deviate from the scientists' theoretical calculations.

This anomaly has only been detected with a high level of precision in flybys of Earth, due to the availability of deep space monitoring stations such as that of NASA in Robledo de Chabela (Madrid) or that of the European Space Agency in Cebreros (Ávila), which allow for the variations in the spacecrafts' speed to be recorded by means of radars.

Thus, when the Galileo space probe flew over Earth in 1990, an unexpected increase of 4 millimetres per second was detected, as was a similar decrease when it took the same flyby in 1992.

Also in 1998, a speed of 13 mm/s above estimates was observed in the spacecraft NEAR, and similar anomalies were repeated in the flybys of Cassini in 1999 (-2 mm/s), and those of the Messenger and Rosetta probes in 2005, with +0.02 mm/s and +1.82 mm/s respectively, the latter arriving just this year at the comet it was directed towards.

"These deviations do not seriously affect the trajectories of the spacecrafts, yet, although they are seemingly small amounts, it is very important to clarify what they are caused by, especially in the current era of precise space exploration," Luis Acedo Rodríguez, physicist at the Polytechnic University of Valencia, tells SINC.

Scientists have still not found any convincing explanation for the phenomenon, although they have put forward a range of hypotheses.

One points toward solar radiation as the cause of the change in speed, while others suggest an influence from magnetic fields or the effect of tides, and there are also even unconventional theories, such as the existence of a halo of dark matter trapped by Earth's gravitational pull.

Acedo has proposed an explanation based on a supposed circulating gravitomagnetic field, which would follow the Earth's parallels, an approach that can be used to explain the effects on the majority of flybys.

"Einstein's general theory of relativity predicts the existence of a similar field, but in the case of meridians, with this strongly confirmed by experiments such as Gravity Probe B," the researcher comments, although he recognises significant limitations of the model.

"If a force field existed," he explains, "its effects would also be seen in the elliptical orbits of spacecrafts, and should have been detected a long time ago by geodynamic satellites such as NASA's LAGEOS or ESA's LARES; however, this is not the case, and it is therefore doubtful that a field of this kind could cast a light on this mystery without seriously changing our understanding of Earth's gravity."

With this possibility ruled out, the expert considers, in a study published in Advances in Space Research, that the anomalous behaviour of the probes during their flybys "must originate in something that, although common, we have been unaware of to date, or in an error in the data analysis programs".

The difference in speeds could also have much more serious implications on the understanding of gravity, according to Acedo: "We already have evidence that shows a seemingly small anomaly in astronomical observations leading to new theoretical conceptions, such as the advance of Mercury's perihelion (closest point to the Sun), which was essential in the development of the theory of general relativity."

"For the case in question, and without ruling out an explanation by means of conventional sources, something similar could occur."

Meanwhile, space probes continue to challenge scientists every time they perform flybys. One of the last was that of the spacecraft Juno in October 2013, from Earth en route to Jupiter.

NASA has not yet published data on this journey, but everything indicates that its speed as it flew over our planet once again differed from estimates.

More information: L. Acedo, "The flyby anomaly: A case for strong gravitomagnetism?," Advances in Space Research, Volume 54, Issue 4, 15 August 2014, Pages 788-796, ISSN 0273-1177, dx.doi.org/10.1016/j.asr.2014.04.014.

Scottish scientists: 'tremendously important' breakthrough in water to hydrogen production process

Chemists in Scotland, at the Cronin laboratory in Glasgow University, have made a major advancement in the process of producing hydrogen from water that may offer cleaner and cheaper gas, and a renewable source of energy.

"The process uses a liquid that allows the hydrogen to be locked up in a liquid-based inorganic fuel," professor Lee Cronin of Glasgow University wrote in the journal Science.

"By using a liquid sponge known as a redox mediator that can soak up electrons and acid we've been able to create a system where hydrogen can be produced in a separate chamber without any additional energy input after the electrolysis of water takes place."

Cronin says the redox mediator allows hydrogen to be produced at 30 times the rate of current processes without requiring more energy.

The new process uses energy from the sun and wind, which, due to lower power outputs, produces significantly less hydrogen.

"Around 95 percent of the world's hydrogen supply is currently obtained from fossil fuels, a finite resource which we know harms the environment and speeds climate change," Cronin's report says.

"The potential for reliable hydrogen production from renewable sources is huge. The sun, for example, provides more energy in a single hour of sunlight than the entire world's population uses in a year."

"If we can tap and store even a fraction of that in the coming years and decrease our reliance on fossil fuels it will be a tremendously important step to slowing climate change."

There is also an ongoing need for Hydrogen extraction from water, coming from the world's space agencies (NASA, ESA, etc) to allow them to occupy, inhabit and produce renewable energy on Mars and other suitable exoplanets outside our Solar System.

Prof Lee Cronin is one of 10 the UK’s most inspirational scientists and engineers named as RISE Leaders for 2014 by the Engineering and Physical Sciences Research Council (EPSRC).

Their contribution to science covers a broad range of disciplines and highlights the diversity and impact of the engineering and physical sciences.

More Information
'Decoupled catalytic hydrogen evolution from a molecular metal oxide redox mediator in water splitting' - Authors: Benjamin Rausch, Mark D. Symes, Greig Chisholm, Leroy Cronin - Science 12 September 2014: Vol. 345 no. 6202 pp. 1326-1330 DOI: 10.1126/science.1257443

Scientists concerned over the future of satellite-based research

Landsat 8 captured fine details of the lava flowing in Iceland between the Bardarbunga and Askja volcanoes.

Credit: NASA, NOAA.

The U.S. has more than 30 civilian, Earth-observing satellites circling the planet, providing scientists with a torrent of crucial environmental and climate information.

More satellites are on deck to launch in the next few years, but, according to an article in Chemical & Engineering News (C&EN), the weekly news magazine of the American Chemical Society, scientists have registered serious concerns over the lack of a long-term, cohesive vision for the scientific missions.

Jyllian Kemsley, a senior editor at C&EN, reports that satellites are marvels of technology.

From their orbits up to thousands of miles above the planet's surface, they collect Earthly measurements and beam down to scientists information they can't get any other way.

The satellites map cloud cover; they track snow and ice cover; they measure atmospheric carbon dioxide, a potent greenhouse gas; they detect chemical reactions in the atmosphere; they help meteorologists make weather predictions.

Future launches will undoubtedly add to the treasure trove of scientific data.

But some scientists say that despite the state-of-the-art sensors the satellites are equipped with, a short-sighted vision for the future, may cause the resulting science to suffer.

They say that the division between two agencies leading the way, NASA, which operates under a "first and best" vision, and the National Oceanic & Atmospheric Administration (NOAA), which takes the longer view, has created a "valley of death."

This gap hinders the use of NASA's research instruments for NOAA's desired sustained monitoring, which is critical to understanding complex systems of atmospheric chemistry and climate.

More information: Observing Earth - cen.acs.org/articles/92/i36/Observing-Earth.html

Scientists discover seamount in Pacific ocean

Three-dimensional view of the southwest side of the seamount with 23-degree slopes. 

Credit: University of New Hampshire

University of New Hampshire scientists on a seafloor mapping mission have discovered a new seamount near the Johnson Atoll in the Pacific Ocean.

The summit of the seamount rises 1,100 meters from the 5,100-meter-deep ocean floor.

The seamount was discovered in August when James Gardner, research professor in the UNH-NOAA Center for Coastal and Ocean Mapping/Joint Hydrographic Center, was leading a mapping mission aimed at helping delineate the outer limits of the U.S. continental shelf.

Working aboard the R/V Kilo Moana, an oceanographic research ship owned by the U.S. Navy and operated by the University of Hawaii, Gardner and his team were using multibeam echosounder technology to create detailed images of the seafloor when, late at night, the seamount appeared "out of the blue." The team was able to map the conical seamount in its entirety.

The yet-unnamed seamount, located about 300 kilometers southeast of the uninhabited Jarvis Island, lies in one of the least explored areas of the central Pacific Ocean. Because of that, Gardner was not particularly surprised by the discovery.

"These seamounts are very common, but we don't know about them because most of the places that we go out and map have never been mapped before," he says.

Since only low-resolution satellite data exists for most of the Earth's seafloor, many seamounts of this size are not resolved in the satellite data but advanced multibeam echosounder missions like this one can resolve them. "Satellites just can't see these features and we can," Gardner adds.

While the mapping mission was in support of the U.S. Extended Continental Shelf Task Force, a multi-agency project to delineate the outer limits of the U.S. continental shelf, the volcanic seamount lies within the U.S. exclusive economic zone.

That means the U.S. has jurisdiction of the waters above it as well as the sediment and rocks of the seamount itself.

Three-dimensional view of the seamount area (southeast point of view and 3.5x vertical exaggeration) showing two volcanoes, in the foreground, with the discovered seamount in the background. 

Credit: University of New Hampshire

The seamount's impact remains unknown – for now. It's too deep (its summit lies nearly 4,000 meters beneath the surface of the ocean) to be a navigation hazard or to provide rich fisheries. "It's probably 100 million years old," Gardner says, "and it might have something in it we may be interested in 100 years from now."

Scientists' research supports discovery mission into Asteroid cores

Dr. Richard S. Miller’s research could influence future asteroid mining operations and how we might deal with an impending strike.

Future asteroid mining operations and how we deal with an impending strike could be influenced by research on a potential NASA mission that's being done by team that includes a University of Alabama in Huntsville (UAH) scientist.

"If you identify an asteroid coming toward us, how you deal with it could depend on its density and structure," says Dr. Richard S. Miller, a UAH physics professor.

"Likewise, if this technique pans out, you could imagine sending out a specialized telescope to determine what the densities and interior structure of various asteroids are, then decide on the basis of that information what ones to mine."

Little is now known about asteroid interior density and composition. Are they uniform or are they what astrophysicists call differentiated bodies, having denser and less-dense areas?

"Asteroids are time capsules of the early solar system," Dr. Miller says.

"We know about their surface properties and we can also infer the mass of some asteroids. But what we want to do is actually probe the interior of asteroids and determine information about their structure, are there interior density gradients, what is the composition, is it solid or like Swiss cheese, and do they have cores or not? Is it a pile of rubble?

It turns out this structure can tell us a great deal about the conditions present during the early epochs of solar system formation and its evolution."

To find that out, the team's scientists will be borrowing imaging technology concepts developed for medicine and high-energy physics.

They are developing a mission concept to probe asteroids using a technique similar to human computerized tomography (CT) scans.

Dr. Miller is a co-investigator in a collaborative effort with the Planetary Science Institute (PSI), NASA's Johnson Space Center, the Universities Space Research Association's Arecibo Observatory (Arecibo/USRA) and the University of Houston to do the fundamental research and design that could lead to such a mission.

Led by principal investigator Dr. Tom Prettyman, senior scientist at PSI, the group has $500,000 in funding from the NASA Innovative Advanced Concepts (NIAC) Phase II program.

The team's two-year proposal, "Deep Mapping of Small Solar System Bodies with Galactic Cosmic Ray Secondary Particle Showers," is one of only five projects selected for funding.

Other funded collaborators include Dr. Steven Koontz, NASA Johnson Space Center; Dr. Michael Nolan, Arecibo/USRA; Dr. Lawrence Pinsky, University of Houston; and Dr. Mark Sykes, PSI.

By detecting the number of muons that pass through the object at left, scientists can discover and measure the size of its core, shown reconstructed at right. 

Credit: Richard S. Miller / UAH

The team proposes using ever-present cosmic rays to perform its measurements.

All objects in space are constantly bombarded by these particles, which are thought to be the remnants of massive supernovas and are primarily protons. On Earth, the atmosphere breaks them up and shields us from direct hits.

"In space, on contact with dense matter like the moon's surface or other airless planetary bodies, they interact within the first few centimeters of depth and create a shower of particles," Dr. Miller says.

Studying those interactions has provided us surface knowledge of asteroids. "But cosmic rays also contain muons, which are particles similar to electrons, but which can go a lot farther into the asteroid, in some cases up to one kilometer."

The idea is to position a telescope to orbit the asteroid and measure the number and trajectories of the muons passing through it.

"Muons are like an SUV," says Dr. Miller. "Once they are moving it is not easy to knock them off their course."

An asteroid composed of varying densities of material would return a different pattern than one with a single density, just as a CT scan differentiates between densities of structures in the body.

Likewise, if an asteroid has a denser core, it will stop muons from passing through and the telescope will detect the change.

That process is called muon tomography and is well understood. Developed in the 1950s, it was even used in the 1960s by Luis Alvarez to map the Pyramid of Chephren.

"What's different about a CT scan is that instead of using cosmic rays and muons to determine densities, a CT scan uses x-rays," Dr. Miller says.

To mature the concept, the scientists must first solve a number of fundamental challenges. They'll be using computer modeling to work on:

• Detailed estimates of the particle signatures, including muons and other radiations that will be present in deep space and in the neighbourhood of any asteroids;
• Doing the initial work on the muon telescope's design and operation. There are competing ideas, and the team will evaluate a variety of performance tradeoffs; 
• The development and implementation of advanced algorithms for asteroid structure reconstruction;
• Establishing the preliminary outlines of how a proposed NASA mission would be conducted, its feasibility and making predictions of the ultimate science return. 

"What it has to do is detect those muons and give us a direction they are coming from," Dr. Miller says of the telescope, but getting to that goal involves tradeoffs.

For example, the bigger the area the telescope can scan as it orbits, the less time it will take to get results encompassing an entire asteroid being studied.

But the greater the telescope's size, the more resources will be involved to launch the mission. Also, to tell where the muons are coming from, the telescope will have to be able to tell directional "up" from "down."

Dr. Miller says he was already exploring using muons to probe asteroids when he attended a conference and found that PSI's Dr. Prettyman was working on the same thing.

"This is a good story of how you had two independent groups who were both looking at the same idea," Dr. Miller says, "and we have joined forces to make a stronger project."

NASA OCO-2 data to lead scientists forward into the past

Scientists will use measurements from the Orbiting Carbon Observatory-2 to track atmospheric carbon dioxide to sources such as these wildfires in Siberia, whose smoke plumes quickly carry the greenhouse gas worldwide. 

The fires were imaged on May 18 by NASA's Moderate Resolution Imaging Spectrometer instrument on the Terra satellite.

Credit: NASA/LANCE/EOSDIS Rapid Response

NASA's Orbiting Carbon Observatory-2, which launched on July 2, will soon be providing about 100,000 high-quality measurements each day of carbon dioxide concentrations from around the globe.

Atmospheric scientists are excited about that but to understand the processes that control the amount of the greenhouse gas in the atmosphere, they need to know more than just where carbon dioxide is now.

They need to know where it has been. It takes more than great data to figure that out.

"In a sense, you're trying to go backward in time and space," said David Baker, a scientist at Colorado State University in Fort Collins.

"You're reversing the flow of the winds to determine when and where the input of carbon at the Earth's surface had to be to give you the measurements you see now."

Harry Potter used a magical time turner to travel to the past. Atmospheric scientists use a type of computer model called a chemical transport model.

It combines the atmospheric processes found in a climate model with additional information on important chemical compounds, including their reactions, their sources on Earth's surface and the processes that remove them from the air, known as sinks.

Baker used the example of a forest fire to explain how a chemical transport model works. "Where the fire is, at that point in time, you get a pulse of carbon dioxide in the atmosphere from the burning carbon in wood.

The model's winds blow it along, and mixing processes dilute it through the atmosphere. It gradually gets mixed into a wider and wider plume that eventually gets blown around the world."

Some models can be run backward in time, from a point in the plume back to the fire, in other words, to search for the sources of airborne carbon dioxide.

The reactions and processes that must be modeled are so complex that researchers often cycle their chemical transport models backward and forward through the same time period dozens of times, adjusting the model as each set of results reveals new clues.

"You basically start crawling toward a solution," Baker said. "You may not be crawling straight toward the best answer, but you course-correct along the way."

Read the full article here

Scientists discover radio emissions are emanating from fireballs

These images show the sky above the first LWA station. 

Each image shows the full sky, down to the horizon at the image's edge.

Streaking across the sky at more than 50 kilometers per second at atmospheric heights of more than a 90 kilometers high, researchers using the first station of University of New Mexico’s Long Wavelength Array (LWA) saw something new that had never been seen before; something that could hold a treasure trove of new information in the world of physics.

Very Large Array (VLA)

The first station of the LWA, known as LWA1, is a unique telescope that consists of a collection of 256 dipoles combined into one massive array with a collective-area of a 100-meter dish.

The LWA1, is a highly sensitive telescope that can create images of the entire sky.

It allows researchers to keep eyes on the whole sky day and night, probing a relatively unexplored region of the electromagnetic spectrum.

Greg Taylor

Within six months of turning LWA1 on, UNM Department of Physics Professor Greg Taylor and his team got the all sky imaging up and running.

Shortly thereafter, they started to search for transients, brief pulses of radio waves coming from the sky.

Ken Obenberger, a UNM graduate student, and colleagues searched for transients in more than 11,000 hours of all-sky images from the LWA at frequencies between 25 and 75 MHz.

In this data he identified 49 long (30 seconds or longer) transients.

"We would see a bright source appear in the sky and it would last for about a minute, and then it would go away," Obenberger said.

"Most of them would come on at one point and then fade away. Sometimes they were a bit extended and a little bit resolved by the telescope, but oftentimes, they weren't," he added.

Long Wavelength Array (LWA)

The University of New Mexico’s Long Wavelength Array (LWA) with the Very Large Array (VLA) in the background.

The research team didn't know what they were exactly and that situation went on for several months.

"When we found an event that streaked over 90 degrees across the sky (see Figure 01 below) we asked ourselves, 'could these be fireballs?'" Taylor asked.

Fireballs are a class of meteor brighter than the planet Venus.

Figure 01: LWA1 image at 38 MHz of a rare fireball that streaked across the sky on Jan. 21, 2014 and left a glowing trail that lasted for over a minute. 

Emission from constant sources has been subtracted for clarity.

To investigate this possibility, the team utilized NASA's All Sky Fireball Network, an observatory consisting of 12 cameras located in the United States.

While most of the cameras are in other states, two are located in southern New Mexico.

The researchers compared the times and locations of the 49 transients with data from the Fireball Network.

They found that 10 of those transients corresponded both spatially and temporarily with fireballs. The optical always precedes the radio Obenberger says.

"You have this bright optical fireball, then slowly the radio emission ramps up. The show is over in the optical stage fairly quickly after a few seconds, but then we have this radio emission lasting for about a minute."

These detections suggest that fireballs emit a low frequency pulse, something that no other telescope has ever seen, and this discovery has provided researchers with new insight into the physics of meteors.

It'll be fun to learn more and it'll give us new information about meteors, their composition or something about the upper atmosphere. It's kind of a whole new ball game." Taylor explained.

More information: "Detection of Radio Emission from Fireballs." K.S. Obenberger, G.B. Taylor, J.M. Hartman, J. Dowell, S.W. Ellingson, J.F. Helmboldt, P.A. Henning, M. Kavic, F.K. Schinzel, J.H. Simonetti, K. Stovall, T.L. Wilson. arxiv.org/abs/1405.6772

Scottish Scientists examine the science of lightning in extrasolar planets

A thunderstorm above Unna, in Germany. 

Credit: S Mial /Wikipedia.

Scientists in Scotland are hoping to make a major 'leap' in working out whether a bolt of lightning could trigger life on planets outside the solar system.

The team, at the University of St Andrews, has been studying lightning in extrasolar planets to better understand how atmospheres on earth become electrically charged.

In turn, the researchers, from the University's LEAP (Life Electricity Atmosphere Planets) group at the School of Physics & Astronomy hope to learn more about the role lightning played in generating the 'building blocks' for life.

Christiane Helling

Lead researcher Dr Christiane Helling will reveal one of her group's findings today at a major meeting involving 11,000 scientists working in the Earth, planetary and space sciences.

The researcher will talk about her work in a special session on lightning at the EGU (European Geosciences Union) General Assembly in Vienna.

Dr Helling said, "Atmospheric electrical discharges, or lightning, have been observed on planets other than Earth such as Jupiter, Uranus and Neptune, but it is very likely that lightning also occurs outside the Solar System too.

"We studied both exoplanets and brown dwarfs, which host clouds made of minerals or gemstones, to see how much energy is deposited into the atmosphere if a lightning strike hits.

A lightning discharge is started by a small-scale 'streamer discharge' which can evolve into a large-scale lightning bolt.

By building a discharge model related to lab works from the University of Eindhoven TU, Dr Helling and her team were able to study the large-scale properties of lightning in extrasolar, cloud-forming atmospheres, and how much energy would be injected by such a lightning strike.

They found that lightning strikes are more energetic in brown dwarfs than in giant gas planets.

"Our work combines plasma physics experiments performed in laboratories on Earth with our research into cloud formation in extrasolar atmospheres," Dr Helling explained.

"Our work tests the physical processes on Earth in non-terrestrial environments such as hydrogen-dominated atmospheres and gemstone clouds outside the solar system, in contrast to the nitrogen-dominated atmosphere and water clouds on Earth."

The St Andrews research could help in extreme situations of lightning on Earth.

More information: Dr Helling will deliver the scientific talk on the topic 'Large-scale properties of lightning in extrasolar objects' on Friday 2 May 2014, 16.45 in room G1 at the EGU conference cite in Vienna. Online: adsabs.harvard.edu/abs/2014ApJ...784...43B

Gamma-ray bursts (GRB): Afterglow discovery surprises scientists

Measurements of polarized light in the afterglow of GRB 120308A by the Liverpool Telescope and its RINGO2 instrument indicate the presence of a large-scale stable magnetic field linked with a young black hole, as shown in this illustration. 

Credit: NASA's Goddard Space Flight Center /S. Wiessinger

Research from an international team of scientists led by the University of Leicester has discovered for the first time that one of the most powerful events in our universe, Gamma-Ray Bursts (GRB), behave differently than previously thought.

The study, published in the prestigious scientific journal Nature, uses evidence from observation of a GRB to rule out most of the existing theoretical predictions concerning the afterglow of the explosions.

Klaas Wiersema

For Dr Klaas Wiersema, of the University of Leicester's Department of Physics and Astronomy, it was handy that he was up in the middle of the night tending to his three-year-old son which is when he got the alert that a GRB had occurred.

He said: "When a suitable GRB is detected by a satellite, I get a text message on my phone, and then I have to very quickly tell the observatory in Chile exactly which observations I want them to take, and how.

"This is usually a rather stressed and frantic few hours of working, as fast as possible, on my laptop throughout our night-time, and I remember very well that my son, who was three at the time, was up a lot that night too, so I kept on running back and forth between my laptop, my phone to call the observatory in Chile, and my son's cot!"

The effort was worth it- and has led to scientific findings that will change theoretical understandings of the afterglows of GRBs.

Dr Wiersema explains: "About once per day, a short, very bright flash of gamma-rays (the most energetic form of light) is detected by satellites. These flashes are called gamma-ray bursts (GRBs), and take place in galaxies far away, when a massive star collapses at the end of its life.

"These GRBs are followed by a so-called "afterglow", slowly fading emission that can be seen at all wavelengths (including visible light), for a few days to weeks."

"We know that the afterglow emission is formed by a shockwave, moving at very high velocities, in which electrons are being accelerated to tremendous energies."

"These fast moving electrons then produce the afterglow light that we detect.

When a massive star dies it explodes as a supernova. 

The core of the star collapses into a black hole, and in care cases a jet is formed along the rotation axis of the newly formed black hole. 

Processes in this jet emits gamma radiation, which we observe as a so-called gamma-ray burst. 

Typically gamma-ray bursts last a few minutes. 

When the jet hits material surrounding the dying star an afterglow is formed. 

New observations of the degree of polarisation of the afterglow light has shown that the afterglow behaves differently than expected 

Credit: NASA

"However, how this acceleration process actually works is very hard to study on Earth in laboratories, or using computer simulations."

"What we do, is study the polarised light of the afterglow using large optical telescopes, and special filters, that work much like the filters in Polaroid sunglasses."

Gamma-ray burst 121024A, as seen on the day of burst by ESO's Very Large Telescope (VLT) in Chile. Only a week later the source had faded completely. 

Credit: Dr Klaas Wiersema, University of Leicester, UK and Dr Peter Curran, ICRAR.

Dr Wiersema says it is important to remember that light is a wave, when light is linearly polarised, it means that the wave vibrations lie in a plane; and when light is circularly polarised, it means that that this plane rotates on the sky.

He added: "Different theories for electron acceleration and light emission within the afterglow all predict different levels of linear polarisation, but theories all agreed that there should be no circular polarisation in visible light."

Peter Curran, ICRAR

"This is where we come in: we decided to test this by carefully measuring both the linear and circular polarisation of one afterglow, of GRB 121024A, detected by the Swift satellite."

"Using the ESO Very Large Telescope (VLT) in Chile, we measured both the linear and circular polarisation of an afterglow with high accuracy."

"Much to our surprise we clearly detected circular polarisation, while theories predicted we should not see any at all."

"We believe that the most likely explanation is that the exact way in which electrons are accelerated within the afterglow shockwave is different from what we always thought."

"It is a very nice example of observations ruling out most of the existing theoretical predictions – exactly why observers like me are in this game!

More information: Paper: Circular polarisation in the optical afterglow of GRB 121024A, Nature, DOI: 10.1038/nature13237

WHOI NEREUS: Scientists use ROV to explore Kermadec Trench‎

Researchers will use the deep-submergence vehicle Nereus in their explorations. 

Credit: WHOI

What lives in the deepest part of the ocean, the abyss?

A team of researchers funded by the National Science Foundation (NSF) will use the world's only full-ocean-depth, hybrid, remotely-operated vehicle, Nereus, and other advanced technology to find out.

They will explore the Kermadec Trench at the bottom of the Pacific Ocean.

The trench, located off New Zealand, is the fifth deepest trench in the world. Its maximum depth is 32,963 feet or 6.24 miles (10,047 meters).

It's also one of the coldest trenches due to the inflow of deep waters from Antarctica.

The 40-day expedition to the Kermadec Trench, which begins on April 12, 2014, kicks off a three-year collaborative effort.

The project, known as the Hadal Ecosystem Studies Project (HADES), will conduct the first systematic study of life in ocean trenches, comparing it to the neighbouring abyssal plains, flat areas of the seafloor usually found at depths between 9,843 and 19,685 feet (3,000 and 6,000 meters).

David Garrison

"The proposal to study the deep-sea environment as part of HADES was high-risk, but, we hope, also high-reward," says David Garrison, program director in NSF's Division of Ocean Sciences, which funds HADES.

"Through this exciting project, we will shine a light into the darkness of Earth's deep-ocean trenches, discovering surprising results all along the way."

Among least-explored environments on Earth
A result of extreme pressures in these deep-sea environments and the technical challenges involved in reaching them, ocean trenches remain among the least-explored environments on the planet.

Tim Shank

"We know relatively little about life in ocean trenches, the deepest marine habitats on Earth," says Tim Shank, a biologist at the Woods Hole Oceanographic Institution, one of the participating organizations.

"We didn't have the technology to do these kinds of detailed studies before. This will be a first-order look at community structure, adaptation and evolution: how life exists in the trenches."

NSF HADES principal investigators are Tim Shank, Jeff Drazen of the University of Hawaii and Paul Yancey of Whitman College.

Telepresence technology aboard the NOAA research vessel Thomas G. Thompson will allow the public to share in the discoveries.

Live-streaming Web events from the seafloor will include narration from the science team.

The researchers' work will also be chronicled in video, still images and blog updates on the expedition website.