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Tuesday, March 31, 2015

100 Million Years Ago: Earliest Fossilized Evidence of an Insect Caring for Its Young


Scientists have uncovered the earliest fossilised evidence of an insect caring for its young.

The findings, published in the journal eLife, push back the earliest direct evidence of insect brood care by more than 50 million years, to at least 100 million years ago when dinosaurs dominated the earth.

The new fossil is the only record of an adult female insect from the Mesozoic, an era that spanned roughly 180 million years. The Mesozoic era was the age of the reptiles and saw both the rise and fall of the dinosaurs, as well as the breakup of the supercontinent Pangaea.

The female ensign scale insect is preserved in a piece of amber retrieved from a mine in northern Myanmar (Burma). The specimen was trapped while carrying around 60 eggs and her first freshly hatched nymphs. The eggs and nymphs are encased in a wax-coated egg sac on the abdomen. This primitive form of brood care protects young nymphs from wet and dry conditions and from natural enemies until they have acquired their own thin covering of wax.
Credit: CCBY 4.0 Wang et al.

The new fossil is the only record of an adult female insect from the Mesozoic, an era that spanned roughly 180 million years. The Mesozoic era was the age of the reptiles and saw both the rise and fall of the dinosaurs, as well as the breakup of the supercontinent Pangaea.

The female ensign scale insect is preserved in a piece of amber retrieved from a mine in northern Myanmar (Burma). The specimen was trapped while carrying around 60 eggs and her first freshly hatched nymphs. The eggs and nymphs are encased in a wax-coated egg sac on the abdomen. This primitive form of brood care protects young nymphs from wet and dry conditions and from natural enemies until they have acquired their own thin covering of wax.

The behaviour has been so successful for promoting the survival of offspring that it is still common in insects today. Young nymphs hatch inside the egg sac and remain there for a few days before emerging into the outside world.

The findings may even offer an explanation for the early diversification of scale insects. The emergence of flowering plants and ants are thought to have been crucial for the rapid evolution of many new insect species, but they were not yet present during the evolutionary history of the ensign scale insects.

"Brood care could have been an important driver for the early radiation of scale insects, which occurred during the end of the Jurassic or earliest Cretaceous period during the Mesozoic era," says lead author Bo Wang, an associate professor at the Chinese Academy of Sciences.

Fossilised evidence of animals caring for their young is extremely rare, especially in insects. Wingless females were largely immobile, so were less likely to be accidentally buried. A cockroach from a similar period was reported carrying a mass of eggs, but cockroaches often deposit their eggs rather than brooding them. The only other direct evidence of brood care is from Cenozoic ambers, the era that extends to the present and began about 65 million years ago with the extinction of the dinosaurs.

"Although analysis seemed to suggest that ancient insects evolved brood care, this is the first direct, unequivocal evidence for the fossil record," says Wang.

The team have named this new species Wathondara kotejai after the goddess of earth in Buddhist mythology and the late Polish entomologist Jan Koteja.



Contacts and sources:

Professor Wang led the international team of scientists from the Chinese Academy of Sciences, the University of Bonn (Germany), the Natural History Museum (London), the University of Silesia, and the University of Gdansk (Poland).

 
Citation: The paper 'Brood care in a 100-million-year-old scale insect' can be freely accessed online athttp://dx.doi.org/10.7554/eLife.05447. Contents, including text, figures, and data, are free to re-use under a CC BY 4.0 license.

Galaxy Clusters Collide; Dark Matter Still A Mystery

Dark matter is one of science's great mysteries. It makes up an enormous amount matter in the universe, it is invisible, and it does not correspond to anything in the realm of our experience. Different theories compete for an explanation, but so far none of them has prevailed. In a collaborative study between École Polytechnique Fédérale de Lausanne (EPFL) and the University of Edinburgh, scientists have studied how dark matter behaves when galaxy clusters collide with each other over billions of years. Published in Science, their findings challenge at least one major theory on dark matter.

Dark matter and galaxy clusters

Although it accounts for 90% of all matter in the universe and more than a quarter of its energy, we know very little about dark matter. One major idea among astronomers is that dark matter consists of a new subatomic particle that we haven't discovered yet. More exotic theories want dark matter to be a quantum defect from the birth of the universe, extra-dimensional mass, and even a modified form of gravity.

The Colliding Spiral Galaxies of Arp 271 

What we do know is that dark matter interacts with cosmic structures through gravity, shaping and molding them. For example, dark matter bends light that passes through it, distorting images of distant space objects. In addition, dark matter speeds up the motion of galaxies inside galaxy clusters, which are collections of hundreds of galaxies, containing literally astronomical amounts of stars, planets, and gases. Galaxy clusters are also 90% dark matter, which makes them ideal for studying it, especially when they collide into each other and force their respective dark matters to interact.

Peering into the dark

David Harvey at EPFL's Laboratory of Astrophysics studies galaxy cluster collisions to find clues about the nature of dark matter. Continuing his PhD work from the Royal Observatory at Edinburgh, he and his colleagues studied data from 72 galaxy cluster collisions. These cosmic crashes happen over the course of billions of years when galaxy clusters attract each other because of their gargantuan masses. When this happens, the dark matter in each galaxy cluster interacts with that of the other, offering a unique opportunity to study it.

Harvey's data came from the Chandra X-ray Space Observatory and the Hubble telescope, and included the famous Bullet Cluster collision, a collision of two galaxy clusters whose gas has been molded into the shape of a bullet. This particular collision is actually the best current evidence for the existence of dark matter.

The researchers analyzed the collision data to measure the change in momentum of dark matter when two galaxy clusters crashed into each other. Experiments on Earth, e.g. in the Large Hadron Collider, show us that when subatomic particles interact, they exchange momentum. Therefore, depending on what happened to the dark matter after the collision, the researchers could draw conclusions about its nature.

To test the theory that dark matter consists of particles, the study worked with two possible scenarios: Either the particles of the dark matter interacted frequently but exchanged little momentum, or they interacted rarely but exchanged a lot of momentum. In the first case, dark matter would slow down after the collision, because the frequent particle interactions would cause an additional "drag". In the second scenario, dark matter would tend to be scattered away and lost into space.

Surprisingly, the study discovered that dark matters in galaxy cluster collisions simply pass through each other. This implies that dark matter particles do not interact with themselves, which would have caused dark matter to slow down. Instead, it appears that while dark matter could interact "non-gravitationally" with visible matter, this is not the case when it interacts with itself.

More importantly, the study challenges the view that dark matter consists of proton-like particles - or perhaps any particles whatsoever. "We have now pushed the probability of two 'dark matter particles' interacting below the probability of two actual protons interacting, which means that dark matter is unlikely to consist of just 'dark-protons'," says David Harvey. "If it did, we would expect to see them 'bounce' off each other".



Contacts and sources:
Nik Papageorgiou
École Polytechnique Fédérale de Lausanne (EPFL)

This work represents a collaboration of EPFL's Laboratory of Astrophysics with the Royal Observatory at the University of Edinburgh, the Institute for Computational Cosmology at Durham University, and the Mullard Space Science Laboratory at University College London.


 Citation: Harvey D, Massey R, Kitching T, Taylor A, Tittley E. The non-gravitational interactions of dark matter in colliding galaxy clusters. Science 27 March 2015. DOI: 10.1126/science.1261381

The Stapes of a Neanderthal Child Points to the Anatomical Differences with Our Species


The Neanderthals (Homo neanderthalensis) inhabited Europe and parts of western Asia between 230,000 and 28,000 years ago; during the last few millennia they coincided with Homo Sapiens Sapiens, and became extinct for reasons that are still being challenged. The archaeological site at La Ferrassie, excavated throughout the 20th century, is a mythical enclave because it was where 7 Neanderthal skeletons, ranging from foetuses to almost complete skeletons of adults, were found.

This is a 3-D reconstruction of the auditory ossicle of a two-year-old Neanderthal.

Credit:  UPV/EHU

Among the remains discovered at La Ferrassie is the skeleton of a 2-year-old Neanderthal child found between 1970 and 1973 and baptised La Ferrassie 8; over 40 years since its discovery it has turned out to be useful in shedding new light on the anatomy of this extinct species.

The study began by reviewing the collections at the Muséum National d'Histoire Naturelle in Paris and at the Museo d'Archéologie national de St. Germain-en-Laye linked to the excavations at La Ferrassie in 1970 and 1973; it was there that 47 new fossils belonging to La Ferrassie 8, which complete its skeleton further, were recovered. Remains of a skull, jaw, vertebrae, ribs and hand phalanges were found among the new fossils.

Featuring among the remains is a very complete left temporal bone and an auditory ossicle was found inside it: a complete stapes. Virtual 3D reconstruction techniques enabled this ossicle to be "extracted virtually" and studied.

This stapes is the most complete one in the Neanderthal record and certifies that there are morphological differences between our species and the Neanderthals even in the smallest ossicles in the human body. As Asier Gómez-Olivencia pointed out, "we do not yet know the relation between these morphological differences and hearing in the Neanderthals. This would constitute a new challenge for the future".

The study of these new remains has been published in the prestigious Journal of Human Evolution, and has also had the participation of researchers of the CNRS (French National Centre for Scientific Research) in Paris and Bordeaux. The fact that a discovery of such significance has been made thanks to reviewing the remains excavated in the 1970s provides the researcher with proof of "the importance and need to review old excavations. We're in no doubt about that".


Contacts and sources:
Matxalen Sotillo


Asier Gómez-Olivencia, a doctor in Human Palaeontology, did research at the University of Cambridge and at the Muséum National d'Histoire Naturelle in France, until 2014 when he joined the UPV/EHU's Department of Stratigraphy and Palaeontology as an Ikerbasque Research Fellow.

Dark Matter Even Darker Than Once Thought


Astronomers using observations from the NASA/ESA Hubble Space Telescope and NASA's Chandra X-ray Observatory have studied how dark matter in clusters of galaxies behaves when the clusters collide. The results, published in the journal Science on 27 March 2015, show that dark matter interacts with itself even less than previously thought, and narrows down the options for what this mysterious substance might be.

This collage shows NASA/ESA Hubble Space Telescope images of six different galaxy clusters. The clusters were observed in a study of how dark matter in clusters of galaxies behaves when the clusters collide. 72 large cluster collisions were studied in total. The clusters shown here are, from left to right and top to bottom: MACS J0416.1-2403, MACS J0152.5-2852, MACS J0717.5+3745, Abell 370, Abell 2744 and ZwCl 1358+62.

Credit:  NASA, ESA, D. Harvey (École Polytechnique Fédérale de Lausanne, Switzerland), R. Massey (Durham University, UK), the Hubble SM4 ERO Team, ST-ECF, ESO, D. Coe (STScI), J. Merten (Heidelberg/Bologna), HST Frontier Fields, Harald Ebeling(University of Hawaii at Manoa), Jean-Paul Kneib (LAM)and Johan Richard (Caltech, USA)

Dark matter is a giant question mark looming over our knowledge of the Universe. There is more dark matter in the Universe than visible matter, but it is extremely elusive; it does not reflect, absorb or emit light, making it invisible. Because of this, it is only known to exist via its gravitational effects on the visible Universe (see e.g. heic1215a).

To learn more about this mysterious substance, researchers can study it in a way similar to experiments on visible matter -- by watching what happens when it bumps into things [1]. For this reason, researchers look at vast collections of galaxies, called galaxy clusters, where collisions involving dark matter happen naturally and where it exists in vast enough quantities to see the effects of collisions [2].

Galaxies are made of three main ingredients: stars, clouds of gas and dark matter. During collisions, the clouds of gas spread throughout the galaxies crash into each other and slow down or stop. The stars are much less affected by the drag from the gas [3] and, because of the huge gaps between them, do not have a slowing effect on each other -- though if two stars did collide the frictional forces would be huge.

"We know how gas and stars react to these cosmic crashes and where they emerge from the wreckage. Comparing how dark matter behaves can help us to narrow down what it actually is," explains David Harvey of the École Polytechnique Fédérale de Lausanne (EPFL) in Switzerland, lead author of a new study.

Harvey and his team used data from the NASA/ESA Hubble Space Telescope and NASA's Chandra X-ray Observatory to study 72 large cluster collisions. The collisions happened at different times, and are seen from different angles -- some from the side, and others head-on [4].

The team found that, like the stars, the dark matter continued straight through the violent collisions without slowing down. However, unlike in the case of the stars, this is not because the dark matter is far away from other dark matter during the collisions. The leading theory is that dark matter is spread evenly throughout the galaxy clusters so dark matter particles frequently get very close to each other. The reason the dark matter doesn't slow down is because not only does it not interact with visible particles, it also interacts even less with other dark matter than previously thought.

"A previous study had seen similar behaviour in the Bullet Cluster," says team member Richard Massey of Durham University, UK. "But it's difficult to interpret what you're seeing if you have just one example. Each collision takes hundreds of millions of years, so in a human lifetime we only get to see one freeze-frame from a single camera angle. Now that we have studied so many more collisions, we can start to piece together the full movie and better understand what is going on."

By finding that dark matter interacts with itself even less than previously thought, the team have successfully narrowed down the properties of dark matter. Particle physics theorists have to keep looking, but they now have a smaller set of unknowns to work with when building their models[5].

Dark matter could potentially have rich and complex properties, and there are still several other types of interaction to study. These latest results rule out interactions that create a strong frictional force, causing dark matter to slow down during collisions. Other possible interactions could make dark matter particles bounce off each other like billiard balls, causing dark matter to be thrown out of collisions or for dark matter blobs to change shape. The team will be studying these next.

To further increase the number of collisions that can be studied, the team are also looking to study collisions involving individual galaxies, which are much more common.

"There are still several viable candidates for dark matter, so the game is not over, but we are getting nearer to an answer," concludes Harvey. "These 'Astronomically Large' particle colliders are finally letting us glimpse the dark world all around us but just out of reach."



Contacts and sources:
Georgia Bladon
ESA/Hubble Information Center

Notes

[1] On Earth scientists use particle accelerators to find out more about the properties of different particles. Physicists can investigate what substances are made of by accelerating particles into a collision, and examining the properties and trajectory of the resulting debris.

[2] Clusters of galaxies are a swarm of galaxies permeated by a sea of hot X-ray emitting ionised hydrogen gas that is all embedded in a massive cloud of dark matter. It is the interactions of these, the most massive structures in the Universe that are observed to test dark matter's properties.

[3] The gas-gas interaction in cluster collisions is very strong, while the gas-star drag is weak. In a similar way to a soap bubble and a bullet in the wind where the bubble would interact a great deal more with the wind than the bullet.

[4] To find out where the dark matter was located in the cluster the researchers studied the light from galaxies behind the cluster whose light had been magnified and distorted by the mass in the cluster. Because they have a good idea of the visible mass in the cluster, the amount the light is distorted tells them how much dark matter there is in a region.

[5] A favoured theory is that dark matter might be constituted of "supersymmetric" particles. Supersymmetry is a theory in which all particles in our Standard Model -- electrons, protons, neutrons, and so on -- have a more massive "supersymmetric" partner. While there has been no experimental confirmation for supersymmetry as yet, the theory would solve a few of the gaps in our current thinking. One of supersymmetry's proposed particles would be stable, electrically neutral, and only interact weakly with the common particles of the Standard Model -- all the properties required to explain dark matter.

Earliest Humans Had Diverse Range Of Body Types, Just As We Do Today


One of the dominant theories of our evolution is that our genus, Homo, evolved from small-bodied early humans to become the taller, heavier and longer legged Homo erectus that was able to migrate beyond Africa and colonise Eurasia. While we know that small-bodied Homo erectus - averaging less than five foot (152cm) and under 50kg - were living in Georgia in southern Europe by 1.77 million years ago, the timing and geographic origin of the larger body size that we associate with modern humans has, until now, remained unresolved.

This is a cast of the 'Nariokotome Boy' (Homo ergaster) skeleton.

Credit: Jay Stock

But a joint study by researchers at the Universities of Cambridge and Tübingen (Germany), published today in the Journal of Human Evolution, has now shown that the main increase in body size occurred tens of thousands of years after Homo erectus left Africa, and primarily in the Koobi Fora region of Kenya. According to Manuel Will, a co-author of the study from the Department of Early Prehistory and Quaternary Ecology at Tübingen, "the evolution of larger bodies and longer legs can thus no longer be assumed to be the main driving factor behind the earliest excursions of our genus to Eurasia".

Researchers say the results from a new research method, using tiny fragments of fossil to estimate our earliest ancestors' height and body mass, also point to the huge diversity in body size we see in humans today emerging much earlier than previously thought.

"What we're seeing is perhaps the beginning of a unique characteristic of our own species - the origins of diversity," said Dr Jay Stock, co-author of the study from the University of Cambridge's Department of Archaeology and Anthropology. "It's possible to interpret our findings as showing that there were either multiple species of early human, such as Homo habilis, Homo ergaster and Homo rudolfensis, or one highly diverse species. This fits well with recent cranial evidence for tremendous diversity among early members of the genus Homo."

This is West Turkana, Kenya, where the Nariokotome boy skeleton was discovered.

Credit:  Manuel Will

"If someone asked you 'are modern humans 6 foot tall and 70kg?' you'd say 'well some are, but many people aren't,' and what we're starting to show is that this diversification happened really early in human evolution," said Stock.

The study is the first in 20 years to compare the body size of the humans who shared the earth with mammoths and sabre-toothed cats between 2.5 and 1.5 million years ago. It is also the first time that many fragmentary fossils - some as small as toes and tiny ankle bones no more than 5cm long - have been used to make body size estimates.

Comparing measurements of fossils from sites in Kenya, Tanzania, South Africa, and Georgia, the researchers found that there was significant regional variation in the size of early humans during the Pleistocene. Some groups, such as those who lived in South African caves, averaged 4.8 feet tall; some of those found in Kenya's Koobi Fora region would have stood at almost 6 foot, comparable to the average of today´s male population in Britain.

"Basically every textbook on human evolution gives the perspective that one lineage of humans evolved larger bodies before spreading beyond Africa. But the evidence for this story about our origins and the dispersal out of Africa just no longer really fits," said Stock. "The first clues came from the site of Dmanisi in Georgia where fossils of really small-bodied people date to 1.77 million years ago. This has been known for several years, but we now know that consistently larger body size evolved in Eastern Africa after 1.7 million years ago, in the Koobi Fora region of Kenya."

"We tend to simplify our interpretations because the fossil record is patchy and we have to explain it in some way. But revealing the diversity that exists is just as important as those broad, sweeping explanations."

Previous studies have been based on small samples of only 10-15 fossils because techniques for calculating the height and body mass of individuals required specific pieces of bone such as the hip joint or most of a leg bone. Stock and Will have used a sample size three times larger, estimating body size for over 40 specimens contained in collections all over Africa and Georgia, making it the largest comparative study conducted so far.

Instead of waiting for new fossils to be discovered and hoping that they contained these specific bones, Stock and Will decided to try a different approach and make use of previously over-looked fossils. In what Stock describes as a "very challenging project," they spent a year developing new equations that allowed them to calculate the height and body mass of individuals using much smaller bones, some as small as toes. By comparing these bones to measurements taken from over 800 modern hunter-gatherer skeletons from around the world and applying various regression equations, the researchers were able to estimate body size for many new fossils that have never been studied in this way before.

"In human evolution we see body size as one of the most important characteristics, and from examining these 'scrappier' fossils we can get a much better sense of when and where human body size diversity arose. Before 1.7 million years ago our ancestors were seldom over 5 foot tall or particularly heavy in body mass.

"When this significant size shift to much heavier, taller individuals happened, it occurred primarily in one particular place - in a region called Koobi Fora in northern Kenya around 1.7 million years ago. That means we can now start thinking about what regional conditions drove the emergence of this diversity, rather than seeing body size as a fixed and fundamental characteristic of a species," said Stock.


Contacts and sources:
Jennifer HaywardUniversity of Cambridge

As Stars Form, Magnetic Fields Influence Regions Big and Small

Stars form when gravity pulls together material within giant clouds of gas and dust. But gravity isn't the only force at work. Both turbulence and magnetic fields battle gravity, either by stirring things up or by channeling and restricting gas flows, respectively. New research focusing on magnetic fields shows that they influence star formation on a variety of scales, from hundreds of light-years down to a fraction of a light-year.

The Cat's Paw Nebula, also known as NGC 6334, comes alive in this infrared image from the Spitzer Space Telescope. A new study of this nebula finds that magnetic fields influence star formation on a variety of scales, from hundreds of light-years down to a fraction of a light-year. In this representative-color photo red shows light at a wavelength of 8 microns, green is 4.5 microns, and blue is 3.6 microns.

Credit:  S. Willis (CfA); NASA/JPL-Caltech/SSC

The new study, which the journal Nature is publishing online on March 30th, probed the Cat's Paw Nebula, also known as NGC 6334. This nebula contains about 200,000 suns' worth of material that is coalescing to form new stars, some with up to 30 to 40 times as much mass as our sun. It is located 5,500 light-years from Earth in the constellation Scorpius.

The team painstakingly measured the orientation of magnetic fields within the Cat's Paw. "We found that the magnetic field direction is quite well preserved from large to small scales, implying that self-gravity and cloud turbulence are not able to significantly alter the field direction," said lead author Hua-bai Li (The Chinese University of Hong Kong), who conducted the high-resolution observations while a post-doctoral fellow at the Harvard-Smithsonian Center for Astrophysics (CfA).

"Even though they're much weaker than Earth's magnetic field, these cosmic magnetic fields have an important effect in regulating how stars form," added Smithsonian co-author T.K. Sridharan (CfA).

The team observed polarized light coming from dust within the nebula using several facilities, including the Smithsonian's Submillimeter Array. "The SMA's unique capability to measure polarization at high angular resolution allowed access to the magnetic fields at the smallest spatial scales," said SMA director Ray Blundell (CfA).

"The SMA has made significant contributions in this field which continues with this work," said Smithsonian co-author Qizhou Zhang (CfA).

Because dust grains align themselves with the magnetic field, the researchers were able to use dust emission to measure the field's geometry. They found that the magnetic fields tended to line up in the same direction, even though the relative size scales they examined were different by orders of magnitude. The magnetic fields only became misaligned on the smallest scales in cases where strong feedback from newly formed stars created other motions.

This work represents the first time magnetic fields in a single region have been measured at so many different scales. It also has interesting implications for the history of our galaxy.

When a molecular cloud collapses to form stars, magnetic fields hinder the process. As a result, only a fraction of the cloud's material is incorporated into stars. The rest gets dispersed into space, where it is available to make new generations of stars. Thanks to magnetic fields, the star-forming process is more drawn out.



Contacts and sources:
Christine Pulliam
Harvard-Smithsonian Center for Astrophysics (CfA)

Mercury Painted Black By Comets


A team of scientists has a new explanation for the planet Mercury's dark, barely reflective surface. In a paper published in Nature Geoscience, the researchers suggest that a steady dusting of carbon from passing comets has slowly painted Mercury black over billions of years.

New research suggests that carbon from cometary material that bombards the Mercury may be the reason the planet's surface is so dark. Experiments show that impact material is significantly darkened when impacts occur in the presence of complex organics.

Credit: NASA/Ames/Brown University

Mercury's dark surface has long been a mystery to scientists. On average, Mercury is much darker than its closest airless neighbor, our Moon. Airless bodies are known to be darkened by micrometeorite impacts and bombardment of solar wind, processes that create a thin coating of dark iron nanoparticles on the surface. But spectral data from Mercury suggests its surface contains very little nanophase iron, certainly not enough to account for its dim appearance.

"It's long been hypothesized that there's a mystery darkening agent that's contributing to Mercury's low reflectance," said Megan Bruck Syal, a postdoctoral researcher at Lawrence Livermore National Laboratory who performed this research while a graduate student at Brown University. "One thing that hadn't been considered was that Mercury gets dumped on by a lot of material derived from comets."

As comets approach Mercury's neighborhood near the sun, they often start to break apart. Cometary dust is composed of as much as 25 percent carbon by weight, so Mercury would be exposed to a steady bombardment of carbon from these crumbling comets. Using a model of impact delivery and a known estimate of micrometeorite flux at Mercury, Bruck Syal was able to estimate how often cometary material would impact Mercury, how much carbon would stick to Mercury's surface, and how much would be thrown back into space. Her calculations suggest that after billions of years of bombardment, Mercury's surface should be anywhere from 3 to 6 percent carbon.

The next part of the work was to find out how much darkening could be expected from all that impacting carbon. For that, the researchers turned to the NASA Ames Vertical Gun Range. The 14-foot canon simulates celestial impacts by firing projectiles at up to 16,000 miles per hour.

For this study, the team launched projectiles in the presence of sugar, a complex organic compound that mimics the organics in comet material. The heat of an impact burns the sugar up, releasing carbon. Projectiles were fired into a material that mimics lunar basalt, the rock that makes up the dark patches on the nearside of the Moon. "We used the lunar basalt model because we wanted to start with something dark already and see if we could darken it further," said Peter Schultz, professor emeritus of geological sciences at Brown and a co-author of the new research.

The experiments showed that tiny carbon particles become deeply embedded in the impact melted material. The process reduced the amount of light reflected by the target material to less than 5 percent -- about the same as the darkest parts of Mercury.

Importantly, spectroscopic analysis of the impact samples revealed no distinctive spectral fingerprints, again similar to flat spectral signatures from Mercury. "We show that carbon acts like a stealth darkening agent," Schultz said. "From the standpoint of spectral analysis, it's like an invisible paint."

And that paint has been building up on Mercury's surface for billions of years.

"We think this is a scenario that needs to be considered," Schultz said. "It appears that Mercury may well be a painted planet."


Contacts and sources:
Kevin Stacey
Brown University

Monday, March 30, 2015

Fired Feds Stole Bitcoins from Silk Road Site During Investigation



Two former federal agents have been charged with wire fraud, money laundering and related offenses for stealing digital currency during their investigation of the Silk Road, an underground black market that allowed users to conduct illegal transactions over the Internet. The charges are contained in a federal criminal complaint issued on March 25, 2015, in the Northern District of California and unsealed today.



Assistant Attorney General Leslie R. Caldwell of the Justice Department’s Criminal Division, U.S. Attorney Melinda Haag of the Northern District of California, Special Agent in Charge David J. Johnson of the FBI’s San Francisco Division, Special Agent in Charge José M. Martinez of the Internal Revenue Service-Criminal Investigation’s (IRS-CI) San Francisco Division, Special Agent in Charge Michael P. Tompkins of the Justice Department’s Office of the Inspector General Washington Field Office and Special Agent in Charge Lori Hazenstab of the Department of Homeland Security’s Office of the Inspector General in Washington D.C. made the announcement.

Carl M. Force, 46, of Baltimore, was a Special Agent with the Drug Enforcement Administration (DEA), and Shaun W. Bridges, 32, of Laurel, Maryland, was a Special Agent with the U.S. Secret Service (USSS). Both were assigned to the Baltimore Silk Road Task Force, which investigated illegal activity in the Silk Road marketplace. Force served as an undercover agent and was tasked with establishing communications with a target of the investigation, Ross Ulbricht, aka “Dread Pirate Roberts.” Force is charged with wire fraud, theft of government property, money laundering and conflict of interest. Bridges is charged with wire fraud and money laundering.

According to the complaint, Force was a DEA agent assigned to investigate the Silk Road marketplace. During the investigation, Force engaged in certain authorized undercover operations by, among other things, communicating online with “Dread Pirate Roberts” (Ulbricht), the target of his investigation. The complaint alleges, however, that Force then, without authority, developed additional online personas and engaged in a broad range of illegal activities calculated to bring him personal financial gain. In doing so, the complaint alleges, Force used fake online personas, and engaged in complex Bitcoin transactions to steal from the government and the targets of the investigation. Specifically, Force allegedly solicited and received digital currency as part of the investigation, but failed to report his receipt of the funds, and instead transferred the currency to his personal account. 

 In one such transaction, Force allegedly sold information about the government’s investigation to the target of the investigation. The complaint also alleges that Force invested in and worked for a digital currency exchange company while still working for the DEA, and that he directed the company to freeze a customer’s account with no legal basis to do so, then transferred the customer’s funds to his personal account. Further, Force allegedly sent an unauthorized Justice Department subpoena to an online payment service directing that it unfreeze his personal account.

Bridges allegedly diverted to his personal account over $800,000 in digital currency that he gained control of during the Silk Road investigation. The complaint alleges that Bridges placed the assets into an account at Mt. Gox, the now-defunct digital currency exchange in Japan. He then allegedly wired funds into one of his personal investment accounts in the United States mere days before he sought a $2.1 million seizure warrant for Mt. Gox’s accounts.

Bridges self-surrendered today and will appear before Magistrate Judge Maria-Elena James of the Northern District of California at 9:30 a.m. PST this morning. Force was arrested on Friday, March 27, 2015, in Baltimore and will appear before Magistrate Judge Timothy J. Sullivan of the District of Maryland at 2:30 p.m. EST today.

The charges contained in the complaint are merely accusations, and the defendants are presumed innocent unless and until proven guilty.

The case was investigated by the FBI’s San Francisco Division, the IRS-CI’s San Francisco Division, the Department of Justice Office of the Inspector General and the Department of Homeland Security Office of the Inspector General in Washington D.C. The Treasury Department’s Financial Crimes Enforcement Network also provided assistance with the investigation of this case. The case is being prosecuted by Assistant U.S. Attorneys Kathryn Haun and William Frentzen of the Northern District of California and Trial Attorney Richard B. Evans of the Criminal Division’s Public Integrity Section.

Source: Department of Justice 

Saturday, March 28, 2015

Microwave Weapon Can Neutralize Aircraft Electrical Systems


Scientific Applications & Research Associates, Inc. (SARA)  (Huntington Beach, CA) has developed a  compact, lightweight, steerable, high-power, microwave weapon.   The aimable, high-power microwave weapon uses a unique antenna to produce a highly focused beam of energy for contacting a target to neutralize the electrically driven systems such as found in missiles, airplanes and automobiles, accompanied by a low impact on human life.

 The antenna can carried on a surface a  truck or air craft along with a feed mechanism such that the antennas are capable of folding into a storage configuration for rapid transport and then expansion into an upright stance for shooting a pencil-thin beam of high-energy microwave radiation at a moving target.   

 The antenna shoots a high-powered microwave energy in a controllable fashion quickly and without the use of traditional large and cumbersome vacuum waveguides.   The high-energy pulsed microwave energy beam  can be used against a moving target to neutralize its electrical control systems without simultaneously exposing the pilot or other human cargo to unhealthy radiation.  

The microwave antenna is unmatched in the rapidity and swath of its beam steering and can be used for directed energy weapons (DEW)  engagements with moving targets both on the ground and in the air.

 The highly steerable antenna is the first of its kind to use  twist-reflector and transreflector technology in a high-power microwave (HPM) capable configuration.

The world's first fully-steerable HPM antenna

Credit:  SARA, Inc.
The power for the microwave is first generated by an internal combustion or jet engine, that feeds to a pulse forming network or Marx bank, that, in turn, drives a high power microwave (HPM) generator, such as s super-reltron, relativistic-magnetron, virtual cathode oscillator, or relativistic Klystron, to produce the microwave radiation for channeling through the waveguide to the feed horn. 

The research and development efforts that produced the technology was funded by the US Army Research Laboratory (ARL).  In May 2003. the weapon earned US Patent # 6,559,807.  

In the patent inventor Robert A. Koslover  says it was determined that a high-peak power microwave transmission, on the order of more than 100 megawatts (MW) of energy, confined to a very tight beam ("pencil beam") using an L-band antenna, lightweight (less than 250 kg) and compact enough to be deployed on a land vehicle or an air platform, could find wide use in intercepting a target and degrading or neutralizing the electronic control monitoring systems and directional control systems in such targets as flying missiles and piloted aircraft as a means of rendering them ineffective without injuring human life.

In other situations, civil authorities may find use for the device to neutralize the electrical system and computer-driven controls of an automobile or other motor vehicle thereby eliminating the need for extended car chase situations by police authorities that often result in destruction of property and severe injury or death to participants and members of the public.






Wednesday, March 25, 2015

Black-hole 'Wind' Linked to a Galactic Gush of Star-forming Gas


By combining observations from the Japan-led Suzaku X-ray satellite and the European Space Agency's infrared Herschel Space Observatory, scientists have connected a fierce "wind" produced near a galaxy's monster black hole to an outward torrent of cold gas a thousand light-years across. The finding validates a long-suspected feedback mechanism enabling a supermassive black hole to influence the evolution of its host galaxy.

"This is the first study directly connecting a galaxy's actively 'feeding' black hole to features found at much larger physical scales," said lead researcher Francesco Tombesi, an astrophysicist at NASA's Goddard Space Flight Center in Greenbelt, Maryland, and the University of Maryland, College Park (UMCP). "We detect the wind arising from the luminous disk of gas very close to the black hole, and we show that it's responsible for blowing star-forming gas out of the galaxy's central regions."

This artist's rendering shows a galaxy being cleared of interstellar gas, the building blocks of new stars. New X-ray observations by Suzaku have identified a wind emanating from the black hole's accretion disk (inset) that ultimately drives such outflows.
Image Credit: ESA/ATG Medialab

Star formation takes place in cold, dense molecular clouds. By heating and dispersing gas that could one day make stars, the black-hole wind forever alters a large portion of its galaxy.

In a study published in the March 26 edition of Nature, Tombesi and his team report the connection in a galaxy known as IRAS F11119+3257, or F11119 for short. The galaxy is so distant, its light has been traveling to us for 2.3 billion years, or about half the present age of our solar system.

Like most galaxies, including our own Milky Way, F11119 hosts a supersized black hole, one estimated at 16 million times the sun's mass. The black hole's activity is fueled by a rotating collection of gas called an accretion disk, which is some hundreds of times the size of our planetary system. Closest to the black hole, the orbiting matter reaches temperatures of millions of degrees and is largely responsible for the galaxy's enormous energy output, which exceeds the sun's by more than a trillion times. The galaxy is heavily enshrouded by dust, so most of this emission reaches us in the form of infrared light.

A red-filter image of IRAS F11119+3257 (inset) from the University of Hawaii's 2.2-meter telescope shows faint features that may be tidal debris, a sign of a galaxy merger. Background: A wider view of the region from the Sloan Digital Sky Survey.

Image Credit: NASA's Goddard Space Flight Center/SDSS/S. Veilleux

The new findings resolve a long-standing puzzle. Galaxies show a correlation between the mass of their central black holes and stellar properties across a much larger region called the galactic bulge. Galaxies with more massive black holes usually possess bulges with proportionately greater stellar mass and faster-moving stars.

Black holes grow the same way their host galaxies do, by colliding and merging with their neighbors. But mergers disrupt galaxies, which leads to greatly enhanced star formation and sends a flood of gas toward the merged black hole. The process should scramble any simple relationship between the black hole's growth and the galaxy's evolution, yet it doesn't.

This animation illustrates how black-hole feedback works in quasars. Dense gas and dust in the center simultaneously fuels the black hole and shrouds it from view. The black-hole wind propels large-scale outflows of cold gas and powers a shock wave that clears gas and dust from the central galaxy.

Image Credit: NASA's Goddard Space Flight Center 

"These connections suggested the black hole was providing some form of feedback that modulated star formation in the wider galaxy, but it was difficult to see how," said team member Sylvain Veilleux, an astronomy professor at UMCP. "With the discovery of powerful molecular outflows of cold gas in galaxies with active black holes, we began to uncover the connection."

In 2013, Veilleux led a search for these outflows in a sample of active galaxies using the Herschel Space Observatory. In F11119, the researchers identified a strong outflow of hydroxyl molecules moving at about 2 million mph (3 million kph). Other studies using different trace molecules found similar flows.

In the present study, Tombesi, Veilleux and their colleagues estimate that this outflow operates up to 1,000 light-years from the galaxy's center and calculate that it removes enough gas to make 800 copies of our sun.

In May 2013, the team observed F11119 using Suzaku's X-ray Imaging Spectrometer, obtaining an effective exposure of nearly three days. The galaxy's spectrum indicates that X-ray-absorbing gas is racing outward from the innermost accretion disk at 170 million mph (270 million kph), or about a quarter the speed of light. The region is possibly half a billion miles (800 million km) from the brink of the black hole, and about as close to the point where not even light can escape as Jupiter is from the sun.

"The black hole is ingesting gas as fast as it can and is tremendously heating the accretion disk, allowing it to produce about 80 percent of the energy this galaxy emits," said co-author Marcio Meléndez, a research associate at UMCP. "But the disk is so luminous some of the gas accelerates away from it, creating the X-ray wind we observe."

Taken together, the disk wind and the molecular outflow complete the picture of black-hole feedback. The black-hole wind sets cold gas and dust into motion, giving rise to the molecular outflow. It also heats dust enshrouding the galaxy, leading to the formation of an outward-moving shock wave that sweeps away additional gas and dust.

When the black hole shines at its brightest, the researchers say, it's also effectively pushing away the dinner plate, clearing gas and dust from the galaxy's central regions and shutting down star formation there. Once the dust has been cleared out, shorter-wavelength light from the disk can escape more easily. 

Scientists think ultra-luminous infrared galaxies like F11119 represent an early phase in the evolution of quasars, a type of black-hole-powered galaxy with extreme luminosity across a broad wavelength range. According to this picture, the black hole will eventually consume its surrounding gas and gradually end its spectacular activity. As it does so, it will evolve from a quasar to a gas-poor galaxy with a relatively low level of star formation.
 
The researchers hope to detect and study this process in other galaxies and look forward to the improved sensitivity of Suzaku's successor, ASTRO-H. Expected to launch in 2016, ASTRO-H is being developed at the Institute of Space and Astronautical Science of the Japan Aerospace Exploration Agency (ISAS/JAXA), in collaboration with NASA Goddard and Japanese institutions.

NASA To Redirect Asteroids, Plans Revealed

NASA Wednesday announced more details in its plan for its Asteroid Redirect Mission (ARM), which in the mid-2020s will test a number of new capabilities needed for future human expeditions to deep space, including to Mars. NASA also announced it has increased the detection of near-Earth asteroids by 65 percent since launching its asteroid initiative three years ago.

The Asteroid Redirect Vehicle conducts one of the 1 km fly-bys that are used to characterize and image the asteroid with a resolution of up to 1 cm.
Credit: NASA

For ARM, a robotic spacecraft will capture a boulder from the surface of a near-Earth asteroid and move it into a stable orbit around the moon for exploration by astronauts, all in support of advancing the nation’s journey to Mars.

Microspine grippers on the end of the robotics arms are used to grasp and secure the boulder. The microspines use thousands of small spines to dig into the boulder and create a strong grip. An integrated drill will be used to provide final anchoring of the boulder to the capture mechanism.
Credit: NASA

"The Asteroid Redirect Mission will provide an initial demonstration of several spaceflight capabilities we will need to send astronauts deeper into space, and eventually, to Mars," said NASA Associate Administrator Robert Lightfoot. "The option to retrieve a boulder from an asteroid will have a direct impact on planning for future human missions to deep space and begin a new era of spaceflight."

Asteroid Capture:  Once the boulder is secured, the ARV will mechanically push off, or “hop,” from the surface and then use thrusters to ascend from the asteroid’s surface.
Credit: NASA

The agency plans to announce the specific asteroid selected for the mission no earlier than 2019, approximately a year before launching the robotic spacecraft. Before an asteroid is considered a valid candidate for the mission, scientists must first determine its characteristics, in addition to size, such as rotation, shape and precise orbit. NASA has identified three valid candidates for the mission so far: Itokawa, Bennu and 2008 EV5. The agency expects to identify one or two additional candidates each year leading up to the mission.

Asteroid Redirect Vehicle Landing: Once the boulder is secured, the Capture and Restraint System legs will provide a mechanical push off that will separate the boulder from the surface and provide an initial ascent without the use of thrusters to limit the amount of debris created.
Credit: NASA

Following its rendezvous with the target asteroid, the uncrewed ARM spacecraft will deploy robotic arms to capture a boulder from its surface. It then will begin a multi-year journey to redirect the boulder into orbit around the moon.

Close-up of the Asteroid Redirect Vehicle departing the asteroid after capturing a boulder from its surface. 
Credit: NASA

Throughout its mission, the ARM robotic spacecraft will test a number of capabilities needed for future human missions, including advanced Solar Electric Propulsion (SEP), a valuable capability that converts sunlight to electrical power through solar arrays and then uses the resulting power to propel charged atoms to move a spacecraft. This method of propulsion can move massive cargo very efficiently. While slower than conventional chemical rocket propulsion, SEP-powered spacecraft require significantly less propellant and fewer launches to support human exploration missions, which could reduce costs.

The asteroid redirect vehicle demonstrates the “gravity tractor” planetary defense technique on a hazardous-size asteroid. The gravity tractor method leverages the mass of the spacecraft to impart a gravitational force on the asteroid, slowly altering the asteroid’s trajectory. The demonstration is conducted after capturing the boulder and is referred to as the “enhanced gravity tractor” because the additional mass of the boulder enhances the force that can be transmitted to the asteroid. 
Credit: NASA

Future SEP-powered spacecraft could pre-position cargo or vehicles for future human missions into deep space, either awaiting crews at Mars or staged around the moon as a waypoint for expeditions to the Red Planet.

The Asteroid Redirect Vehicle travels toward a stable orbit around the moon with the captured asteroid boulder. The vehicle’s solar arrays collect power from the sun and convert it to energy to ionize and accelerate xenon propellant, resulting in the bright blue plume at the rear of the vehicle.

Credit: NASA

ARM's SEP-powered robotic spacecraft will test new trajectory and navigation techniques in deep space, working with the moon's gravity to place the asteroid in a stable lunar orbit called a distant retrograde orbit. This is a suitable staging point for astronauts to rendezvous with a deep space habitat that will carry them to Mars.

An astronaut, anchored to a foot restraint, prepares to investigate the asteroid boulder.

Credit: NASA

Before the piece of the asteroid is moved to lunar orbit, NASA will use the opportunity to test planetary defense techniques to help mitigate potential asteroid impact threats in the future. The experience and knowledge acquired through this operation will help NASA develop options to move an asteroid off an Earth-impacting course, if and when that becomes necessary.

In 2005, NASA's Deep Impact comet science mission tested technology that could assist in changing the course of a near-Earth object using a direct hit with a spacecraft. The ARM robotic spacecraft opens a new and second option for planetary defense using a technique called a gravity tractor. All mass exerts and experiences gravity and, in space, the gravitational attraction even between masses of modest size can significantly affect their motion. This means that by rendezvousing with the asteroid and holding a halo orbit in the appropriate direction, the ARM robotic spacecraft can slowly pull the asteroid without touching it. The effectiveness of this maneuver is increased, moreover, if mass is moved from the asteroid to the spacecraft by the capture of a boulder.

The Asteroid Redirect Vehicle descends to the asteroid’s surface following a series of dry-runs that are used to verify vehicle performance. 
Credit: NASA

It will take approximately six years for the ARM robotic spacecraft to move the asteroid mass into lunar orbit. In the mid-2020s, NASA's Orion spacecraft will launch on the agency’s Space Launch System rocket, carrying astronauts on a mission to rendezvous with and explore the asteroid mass. The current concept for the crewed mission component of ARM is a two-astronaut, 24-25 day mission.

This crewed mission will further test many capabilities needed to advance human spaceflight for deep space missions to Mars and elsewhere, including new sensor technologies and a docking system that will connect Orion to the robotic spacecraft carrying the asteroid mass. Astronauts will conduct spacewalks outside Orion to study and collect samples of the asteroid boulder wearing new spacesuits designed for deep space missions.

Collecting these samples will help astronauts and mission managers determine how best to secure and safely return samples from future Mars missions. And, because asteroids are made of remnants from the formation of the solar system, the returned samples could provide valuable data for scientific research or commercial entities interested in asteroid mining as a future resources.
 
In 2012, the president's NASA budget included, and Congress authorized, $20.4 million for an expanded NASA Near-Earth Object (NEO) Observations Program, increasing the resources for this critical program from the $4 million per year it had received since the 1990s. The program was again expanded in fiscal year 2014, with a budget of $40.5 million. NASA is asking Congress for $50 million for this important work in the 2016 budget.

"Asteroids are a hot topic," said Jim Green, director of NASA Planetary Science. "Not just because they could pose a threat to Earth, but also for their scientific value and NASA's planned mission to one as a stepping stone to Mars."

NASA has identified more than 12,000 NEOs to date, including 96 percent of near-Earth asteroids larger than 0.6 miles (1 kilometer) in size. NASA has not detected any objects of this size that pose an impact hazard to Earth in the next 100 years. Smaller asteroids do pass near Earth, however, and some could pose an impact threat. In 2011, 893 near-Earth asteroids were found. In 2014, that number was increased to 1,472.

In addition to NASA's ongoing work detecting and cataloging asteroids, the agency has engaged the public in the hunt for these space rocks through the agency's Asteroid Grand Challenge activities, including prize competitions. During the recent South by Southwest Festival in Austin, Texas, the agency announced the release of a software application based on an algorithm created by a NASA challenge that has the potential to increase the number of new asteroid discoveries by amateur astronomers.

 
Contacts and sources:
David E. Steitz / Karen Northon
NASA

Jupiter's Grand Attack on the Inner Solar System

Jupiter may have swept through the early solar system like a wrecking ball, destroying a first generation of inner planets before retreating into its current orbit, according to a new study published March 23 in Proceedings of the National Academy of Sciences. The findings help explain why our solar system is so different from the hundreds of other planetary systems that astronomers have discovered in recent years.

Jupiter is thought to have migrated inward toward the sun before retreating to its current position in the solar system. 
Photo credit: NASA/Cassini

"Now that we can look at our own solar system in the context of all these other planetary systems, one of the most interesting features is the absence of planets inside the orbit of Mercury," said Gregory Laughlin, professor and chair of astronomy and astrophysics at UC Santa Cruz and coauthor of the paper. "The standard issue planetary system in our galaxy seems to be a set of super-Earths with alarmingly short orbital periods. Our solar system is looking increasingly like an oddball."

The new paper explains not only the "gaping hole" in our inner solar system, he said, but also certain characteristics of Earth and the other inner rocky planets, which would have formed later than the outer planets from a depleted supply of planet-forming material.

Laughlin and coauthor Konstantin Batygin explored the implications of a leading scenario for the formation of Jupiter and Saturn. In that scenario, proposed by another team of astronomers in 2011 and known as the "Grand Tack," Jupiter first migrated inward toward the sun until the formation of Saturn caused it to reverse course and migrate outward to its current position. 

This diagram shows the orbital distribution of extrasolar planets smaller than Jupiter that have been detected by the Kepler mission, in comparison to the orbits of Mercury, Venus, Earth, and Mars. Most of these extrasolar planets are much closer to their host stars than the innermost planets of our solar system are to the sun.

Credit: Batygin and Laughlin, PNAS

Batygin, who first worked with Laughlin as an undergraduate at UC Santa Cruz and is now an assistant professor of planetary science at the California Institute of Technology, performed numerical calculations to see what would happen if a set of rocky planets with close-in orbits had formed prior to Jupiter's inward migration.

At that time, it's plausible that rocky planets with deep atmospheres would have been forming close to the sun from a dense disk of gas and dust, on their way to becoming typical "super-Earths" like so many of the exoplanets astronomers have found around other stars. As Jupiter moved inward, however, gravitational perturbations from the giant planet would have swept the inner planets (and smaller planetesimals and asteroids) into close-knit, overlapping orbits, setting off a series of collisions that smashed all the nascent planets into pieces.

"It's the same thing we worry about if satellites were to be destroyed in low-Earth orbit. Their fragments would start smashing into other satellites and you'd risk a chain reaction of collisions. Our work indicates that Jupiter would have created just such a collisional cascade in the inner solar system," Laughlin said.

The resulting debris would then have spiraled into the sun under the influence of a strong "headwind" from the dense gas still swirling around the sun. The ingoing avalanche would have destroyed any newly-formed super-Earths by driving them into the sun. A second generation of inner planets would have formed later from the depleted material that was left behind, consistent with evidence that our solar system's inner planets are younger than the outer planets. The resulting inner planets--Mercury, Venus, Earth, and Mars--are also less massive and have much thinner atmospheres than would otherwise be expected, Laughlin said.

"One of the predictions of our theory is that truly Earth-like planets, with solid surfaces and modest atmospheric pressures, are rare," he said.

Planet hunters have detected well over a thousand exoplanets orbiting stars in our galaxy, including nearly 500 systems with multiple planets. What has emerged from these observations as the "typical" planetary system is one consisting of a few planets with masses several times larger than the Earth's (called super-Earths) orbiting much closer to their host star than Mercury is to the sun. In systems with giant planets similar to Jupiter, they also tend to be much closer to their host stars than the giant planets in our solar system. The rocky inner planets of our solar system, with relatively low masses and thin atmospheres, may turn out to be fairly anomalous.

According to Laughlin, the formation of giant planets like Jupiter is somewhat rare, but when it occurs the giant planet usually migrates inward and ends up at an orbital distance similar to Earth's. Only the formation of Saturn in our own solar system pulled Jupiter back out and allowed Mercury, Venus, Earth, and Mars to form. Therefore, another prediction of the paper is that systems with giant planets at orbital periods of more than about 100 days would be unlikely to host multiple close-in planets, Laughlin said.

"This kind of theory, where first this happened and then that happened, is almost always wrong, so I was initially skeptical," he said. "But it actually involves generic processes that have been extensively studied by other researchers. There is a lot of evidence that supports the idea of Jupiter's inward and then outward migration. Our work looks at the consequences of that. Jupiter's 'Grand Tack' may well have been a 'Grand Attack' on the original inner solar system."

In a 2010 study, scientists say baby Jupiter was so strongly bashed by giant Earths that it lost part of its core. That would explain why Jupiter's core is disproportionately smaller today than sibling planet Saturn, says astronomer Douglas Lin, with the University of California in Santa Cruz.  

Scientists suspect that gas giant planets like Jupiter and Saturn started off with rocky and/or icy bodies about 10 times the mass of Earth. At that point, their gravitational muscles would be strong enough to begin pulling gas from the surrounding region, causing them to balloon in size over time. 

"In principle, all gas giants need to get to a critical core mass before they can start to accrete gas," Lin told Discovery News. "So the question is: Why is Jupiter's core mass so much smaller than Saturn's even though its total mass is so much bigger?" 

Working with computer models, astronomers Shu Lin Li of Peking University in China, Craig Agnor with Queen Mary University of London, and Lin came up with one possible answer: Perhaps Jupiter started off like Saturn, but lost part of its core as it evolved. The scientists calculated that if an object roughly five times the mass of Earth hit Jupiter, the impact would strike all the way to the planet's core. Add another three or four crashes and Jupiter's core would be eroded to roughly what it is today. 

"Jupiter has always had this problem because if we believe the numbers... the core seems to be too small -- so small that it cannot accrete gas efficiently in the solar nebula. This scenario gets around the problem," Lin said. 


Contacts and sources:
Tim Stephens
University of California in Santa Cruz

Monday, March 23, 2015

Darwinian Puzzle Key Found


Scientific screening techniques developed by our researchers have solved an important evolutionary puzzle that has baffled palaeontologists for more than a century.


Credit: York University

The remarkable technical feat casts new light on the origins of Toxodon and Macrauchenia, South American ungulates or hooved animals, described by Charles Darwin as the ‘strangest animals ever discovered’.

Previous attempts by scientists to pinpoint the origin of the animals using morphology-based analysis and DNA analysis of fossils had failed.

But techniques refined by experts in our BioArCh research facility and Centre of Excellence in Mass Spectrometry uncovered evidence that the animals were related to mammals like horses - rather than elephants and other African species as some taxonomists have maintained.

The breakthrough came when the researchers switched to analysing collagen samples, a structural protein that can survive around ten times longer than DNA. The team at York team screened 48 fossil bone samples of Toxodon platensis and Macrauchenia patachonica discovered in the 19th century in the same area as those recovered by Darwin.

Credit: W. Norton Publishers (in production).

Family tree

They produced sequences covering more than 90 per cent of the collagen molecule, providing a phylogenetic family ‘tree’ for the two species.

This is the first time the technique has produced molecular information based on protein sequences from the time of the last Ice Age, opening up the potential for further important evolutionary insights.

“People have been successful in retrieving collagen sequences from specimens dating up to four million years old and this is just the start,” said Professor Matthew Collins of BioArCh who carried out the sequencing work with Professor Jane Thomas-Oates, director of York’s Centre of Excellence in Mass Spectrometry. “In theory, with material recovered from permafrost conditions, we might be able to reach back ten million years or more.”

Exploring the evolutionary process

He added: “We now have the potential to address many more of these challenges and to explore the evolutionary process much further back in prehistory.”

The research team also included York PhD student Frido Welker and Dr Jessica Thomas from the University’s Department of Biology.

The Natural History Museum and the American Museum of Natural History led the project which was funded through the Systematics and Taxonomy research scheme (SynTax) supported by the Systematics Association, Linnean Society and the Biotechnology and Biological Sciences Research Council and the Natural Environment Research Council. The research is published in Nature.

Toxodon and Macrauchenia disappeared around 10,000 years ago. The 1.5 ton rhinoceros-sized Toxodon was the most common large-hoofed mammal to roam South America during the Late Pliocene and Plesistocene period over 16,500 years ago. The more nimble Macrauchenia, or ‘long llama’ resembled a humpless camel – but with a short trunk-like snout.

Charles Darwin collected fossils of the animals 180 years ago in Uruguay and Argentina during a stop-over on his famous journey on board The Beagle.


Contacts and sources:
Professor Mathew Collins

The Sound of Stars Discovered

A chance discovery by a team of researchers, including a University of York scientist, has provided experimental evidence that stars may generate sound.

Star formation in the Large Magellanic Cloud
 Credit; ESO 

The study of fluids in motion – now known as hydrodynamics – goes back to the Egyptians, so it is not often that new discoveries are made. However when examining the interaction of an ultra-intense laser with a plasma target, the team observed something unexpected.

Scientists including Dr John Pasley, of the York Plasma Institute in the Department of Physics at York, realised that in the trillionth of a second after the laser strikes, plasma flowed rapidly from areas of high density to more stagnant regions of low density, in such a way that it created something like a traffic jam. Plasma piled up at the interface between the high and low density regions, generating a series of pressure pulses: a sound wave.

However, the sound generated was at such a high frequency that it would have left even bats and dolphins struggling! With a frequency of nearly a trillion hertz, the sound generated was not only unexpected, but was also at close to the highest frequency possible in such a material – six million times higher than that which can be heard by any mammal!

Dr Pasley, who worked with scientists from the Tata Institute of Fundamental Research in Mumbai, India, and the Science and Technology Facilities Council’s Central Laser Facility in Oxfordshire, said: “One of the few locations in nature where we believe this effect would occur is at the surface of stars. When they are accumulating new material stars could generate sound in a very similar manner to that which we observed in the laboratory – so the stars might be singing – but, since sound cannot propagate through the vacuum of space, no-one can hear them.”

The technique used to observe the sound waves in the laboratory works very much like a police speed camera. It allows the scientists to accurately measure how fluid is moving at the point that is struck by the laser on timescales of less than a trillionth of a second.

Dr Alex Robinson from the Plasma Physics Group at STFC’s Central Laser Facility developed a numerical model to generate acoustic waves for the experiment. He said, “It was initially hard to determine the origin of the acoustic signals, but our model produced results that compared favourably with the wavelength shifts observed in the experiment. This showed that we had discovered a new way of generating sound from fluid flows. Similar situations could occur in plasma flowing around stars.”

The research was funded by the Engineering and Physical Sciences Research Council and the Tata Institute of Fundamental Research. It is published in Physical Review Letters.



Contacts and sources:
David Garner
University of York

Citaiton:  Terahertz acoustics in hot dense laser-plasmas by Amitava Adak, A. P. L. Robinson, Prashant Kumar Singh, et al is published in Physical Review Letters.

Doomsday Asteroid Strikes Found in Australia; Left World's Largest Impact Zone

A 400 kilometre-wide impact zone from a huge meteorite that broke in two moments before it slammed into the Earth has been found in Central Australia.

The crater from the impact millions of years ago has long disappeared. But a team of geophysicists has found the twin scars of the impacts – the largest impact zone ever found on Earth – hidden deep in the earth’s crust.

Dr Andrew Glikson with a sample of suevite - a rock with partially melted material formed during an impact. 

Image: D. Seymour

Lead researcher Dr Andrew Glikson from the ANU School of Archaeology and Anthropologysaid the impact zone was discovered during drilling as part of geothermal research, in an area near the borders of South Australia, Queensland and the Northern Territory.

“The two asteroids must each have been over 10 kilometres across – it would have been curtains for many life species on the planet at the time,” said Dr Glikson.

Their paper reports geophysical anomalies and intra-crystalline quartz lamellae in drill cores from the Warburton West Basin overlapping the border of South Australia and the Northern Territory. The pre-Upper Carboniferous ~ 450 × 300 km-large Warburton Basin, north-eastern South Australia, is marked by distinct eastern and western magnetic, gravity and low-velocity seismic tomography anomalies.

Warburton East and West sub-basins, northeast South Australia; the Birdsville Track Ridge divides the Warburton East Basin from the Warburton West Basin. 

Credit: Andrew Glikson et al.

The revelation of such ancient violent impacts may lead to new theories about the Earth’s history.

“Large impacts like these may have had a far more significant role in the Earth’s evolution than previously thought,” Dr Glikson said.

The exact date of the impacts remains unclear. The surrounding rocks are 300 to 600 million years old, but evidence of the type left by other meteorite strikes is lacking.

For example, a large meteorite strike 66 million years ago sent up a plume of ash which is found as a layer of sediment in rocks around the world. The plume is thought to have led to the extinction of a large proportion of the life on the planet, including many dinosaur species.

Wharburton Basin 

Credit: Google Earth

However, a similar layer has not been found in sediments around 300 million years old, Dr Glikson said.

“It’s a mystery – we can’t find an extinction event that matches these collisions. I have a suspicion the impact could be older than 300 million years,” he said.

A geothermal research project chanced on clues to the impacts while drilling more than two kilometres into the earth’s crust.

The drill core contained traces of rocks that had been turned to glass by the extreme temperature and pressure caused by a major impact.

Magnetic modelling of the deep crust in the area traced out bulges hidden deep in the Earth, rich in iron and magnesium, corresponding to the composition of the Earth mantle.

“There are two huge deep domes in the crust, formed by the Earth’s crust rebounding after the huge impacts, and bringing up rock from the mantle below,” Dr Glikson said.

The two impact zones total more than 400 kilometres across, in the Warburton Basin in Central Australia. They extend through the Earth’s crust, which is about 30 kilometres thick in this area.

The research has been published in journal Tectonophysics.


Contacts and sources:
Dr Phil Dooley

Citation: Geophysical anomalies and quartz deformation of the Warburton West structure, central Australia: Authors:  A.Y. Glikson,  A.J. Meixner, B. Radke, I.T. Uysal, E. Saygin, J. Vickers, 
T.P. Mernagh 

Sunday, March 22, 2015

Prehistoric Stone Tools Bear 500,000-Year-Old Animal Residue

Tel Aviv Univeisty (TAU) discovers first direct evidence early flint tools were used to butcher animal carcasses.

Some 2.5 million years ago, early humans survived on a paltry diet of plants. As the human brain expanded, however, it required more substantial nourishment — namely fat and meat — to sustain it. This drove prehistoric man, who lacked the requisite claws and sharp teeth of carnivores, to develop the skills and tools necessary to hunt animals and butcher fat and meat from large carcasses.

An elephant rib bearing cutmarks associated with flint tools at the Revadim site.

Credit:  American Friends of Tel Aviv University (AFTAU)

Among elephant remains some 500,000 years old at a Lower Paleolithic site in Revadim, Israel, Prof. Ran Barkai and his graduate students Natasha Solodenko and Andrea Zupanchich of Tel Aviv University's Department of Archaeology and Ancient Near Eastern Cultures recently analyzed "handaxes" and "scrapers," universally shaped and sized prehistoric stone tools, replete with animal residue.

The research, published recently in PLOS One, represents the first scientifically verified direct evidence for the precise use of Paleolithic stone tools: to process animal carcasses and hides. The research was done in collaboration with Drs. Stella Ninziante Cesaro and Cristina Lemorini of La Sapienza, University of Rome, and Dr. Ofer Marder of Ben-Gurion University of the Negev.

Putting the puzzle together

"There are three parts to this puzzle: the expansion of the human brain, the shift to meat consumption, and the ability to develop sophisticated technology to meet the new biological demands. The invention of stone technology was a major breakthrough in human evolution," Prof. Barkai said. "Fracturing rocks in order to butcher and cut animal meat represents a key biological and cultural milestone.

"At the Revadim quarry, a wonderfully preserved site a half-million years old, we found butchered animal remains, including an elephant rib bone which had been neatly cut by a stone tool, alongside flint handaxes and scrapers still retaining animal fat. It became clear from further analyses that butchering and carcass processing indeed took place at this site."

Through use-wear analysis — examining the surfaces and edges of the tools to determine their function — and the Fourier Transform InfraRed (FTIR) residue analysis which harnesses infrared to identify signatures of prehistoric organic compounds, the researchers were able to demonstrate for the first time direct proof of animal exploitation by flint tools.

"Archaeologists have until now only been able to suggest scenarios about the use and function of such tools. We don’t have a time machine," Prof. Barkai said. "It makes sense that these tools would be used to break down carcasses, but until evidence was uncovered to prove this, it remained just a theory."

A prehistoric Swiss army knife

While the question of their function and production remained unanswered until now, there was little doubt that the handaxe and scraper, found at prehistoric sites all around the world, were distinct, used for specific purposes. By replicating the flint tools for a modern butchering experiment, and then comparing the replicas with their prehistoric counterparts, the researchers determined that the handaxe was prehistoric man's sturdy "Swiss army knife," capable of cutting and breaking down bone, tough sinew, and hide. The slimmer, more delicate scraper was used to separate fur and animal fat from muscle tissue.

"Prehistoric peoples made use of all parts of the animal," said Prof. Barkai. "In the case of the massive elephant, for example, they would have needed to use both tools to manage such a challenging task. The knowledge of how to make these tools was precious, and must have been passed along from generation to generation, because these tools were reproduced the same way across great territorial expanses and over hundreds of thousands of years.

"In this thousand-piece puzzle called archaeology, sometimes we find pieces that connect other pieces together. This is what we have found with the stone tools and animal bones."


Contacts and sources:

Did a Volcanic Cataclysm 40,000 Years Ago Trigger the Final Demise of the Neanderthals?

The Campanian Ignimbrite (CI) eruption in Italy 40,000 years ago was one of the largest volcanic cataclysms in Europe and injected a significant amount of sulfur-dioxide (SO2) into the stratosphere. Scientists have long debated whether this eruption contributed to the final extinction of the Neanderthals. This new study by Benjamin A. Black and colleagues tests this hypothesis with a sophisticated climate model.

This image shows annually averaged temperature anomalies in excess of 3°C for the first year after the Campanian Ignimbrite (CI) eruption compared with spatial distribution of hominin sites with radiocarbon ages close to that of the eruption.

Credit: B.A. Black et al. and the journal Geology

Black and colleagues write that the CI eruption approximately coincided with the final decline of Neanderthals as well as with dramatic territorial and cultural advances among anatomically modern humans. Because of this, the roles of climate, hominin competition, and volcanic sulfur cooling and acid deposition have been vigorously debated as causes of Neanderthal extinction.

They point out, however, that the decline of Neanderthals in Europe began well before the CI eruption: "Radiocarbon dating has shown that at the time of the CI eruption, anatomically modern humans had already arrived in Europe, and the range of Neanderthals had steadily diminished. Work at five sites in the Mediterranean indicates that anatomically modern humans were established in these locations by then as well."

"While the precise implications of the CI eruption for cultures and livelihoods are best understood in the context of archaeological data sets," write Black and colleagues, the results of their study quantitatively describe the magnitude and distribution of the volcanic cooling and acid deposition that ancient hominin communities experienced coincident with the final decline of the Neanderthals.

In their climate simulations, Black and colleagues found that the largest temperature decreases after the eruption occurred in Eastern Europe and Asia and sidestepped the areas where the final Neanderthal populations were living (Western Europe). Therefore, the authors conclude that the eruption was probably insufficient to trigger Neanderthal extinction.

However, the abrupt cold spell that followed the eruption would still have significantly impacted day-to-day life for Neanderthals and early humans in Europe. Black and colleagues point out that temperatures in Western Europe would have decreased by an average of 2 to 4 degrees Celsius during the year following the eruption. These unusual conditions, they write, may have directly influenced survival and day-to-day life for Neanderthals and anatomically modern humans alike, and emphasize the resilience of anatomically modern humans in the face of abrupt and adverse changes in the environment.


Contacts and sources:
Kea Giles
The Geological Society of America

Citation: Campanian Ignimbrite volcanism, climate, and the final decline of the Neanderthals
Benjamin A. Black et al., University of California, Berkeley, California, USA. Published online ahead of print on 19 March 2015; http://dx.doi.org/10.1130/G36514.1.