How Did Earth's Primitive Chemistry Get Kick Started?

This image from the floor of the Atlantic Ocean shows a collection of limestone towers known as the "Lost City." Alkaline hydrothermal vents of this type are suggested to be the birthplace of the first living organisms on the ancient Earth. Scientists are interested in understanding early life on Earth because if we ever hope to find life on other worlds - especially icy worlds with subsurface oceans such as Jupiter's moon Europa and Saturn's Enceladus - we need to know what chemical signatures to look for.
Image courtesy D. Kelley and M. Elend/University of Washington

How did life on Earth get started? Three new papers co-authored by Mike Russell, a research scientist at NASA's Jet Propulsion Laboratory, Pasadena, Calif., strengthen the case that Earth's first life began at alkaline hydrothermal vents at the bottom of oceans. Scientists are interested in understanding early life on Earth because if we ever hope to find life on other worlds -- especially icy worlds with subsurface oceans such as Jupiter's moon Europa and Saturn's Enceladus -- we need to know what chemical signatures to look for. 

Two papers published recently in the journal Philosophical Transactions of the Royal Society B provide more detail on the chemical and precursor metabolic reactions that have to take place to pave the pathway for life. Russell and his co-authors describe how the interactions between the earliest oceans and alkaline hydrothermal fluids likely produced acetate (comparable to vinegar). The acetate is a product of methane and hydrogen from the alkaline hydrothermal vents and carbon dioxide dissolved in the surrounding ocean. Once this early chemical pathway was forged, acetate could become the basis of other biological molecules. They also describe how two kinds of "nano-engines" that create organic carbon and polymers -- energy currency of the first cells -- could have been assembled from inorganic minerals. 

A paper published in the journal Biochimica et Biophysica Acta analyzes the structural similarity between the most ancient enzymes of life and minerals precipitated at these alkaline vents, an indication that the first life didn't have to invent its first catalysts and engines. 

"Our work on alkaline hot springs on the ocean floor makes what we believe is the most plausible case for the origin of the life's building blocks and its energy supply," Russell said. "Our hypothesis is testable, has the right assortment of ingredients and obeys the laws of thermodynamics." 

Russell's work was funded by the NASA Astrobiology Institute through the Icy Worlds team based at JPL, a division of the California Institute of Technology, Pasadena. The NASA Astrobiology Institute, based at NASA's Ames Research Center, Moffett Field, Calif., is a partnership among NASA, 15 U.S. teams and 13 international consortia. The Institute is part of NASA's astrobiology program, which supports research into the origin, evolution, distribution and future of life on Earth and the potential for life elsewhere.

Source :  NASA/Jet Propulsion Laboratory.

By Science and Universe

Planetary 'Runaway Greenhouse' More Easily Triggered, Research Shows

Venus. In the runaway greenhouse stage, a planet absorbs more solar energy than it can give off to retain equilibrium. As a result, the world overheats, boiling its oceans and filling its atmosphere with steam, which leaves the planet glowing-hot and forever uninhabitable, as Venus is now. (Credit: NASA/JPL)

It might be easier than previously thought for a planet to overheat into the scorchingly uninhabitable “runaway greenhouse” stage, according to new research by astronomers at the University of Washington and the University of Victoria published July 28 in the journal Nature Geoscience.

In the runaway greenhouse stage, a planet absorbs more solar energy than it can give off to retain equilibrium. As a result, the world overheats, boiling its oceans and filling its atmosphere with steam, which leaves the planet glowing-hot and forever uninhabitable, as Venus is now.

One estimate of the inner edge of a star’s “habitable zone” is where the runaway greenhouse process begins. The habitable zone is that ring of space around a star that’s just right for water to remain in liquid form on an orbiting rocky planet’s surface, thus giving life a chance.

Revisiting this classic planetary science scenario with new computer modeling, the astronomers found a lower thermal radiation threshold for the runaway greenhouse process, meaning that stage may be easier to initiate than had been previously thought.

“The habitable zone becomes much narrower, in the sense that you can no longer get as close to the star as we thought before going into a runaway greenhouse,” said Tyler Robinson, a UW astronomy postdoctoral researcher and second author on the paper. The lead author is Colin Goldblatt of the University of Victoria.

Though further research is called for, the findings could lead to a recalibration of where the habitable zone begins and ends, with some planets having their candidacy as possible habitable worlds revoked.

“These worlds on the very edge got ‘pushed in,’ from our perspective — they are now beyond the runaway greenhouse threshold,” Robinson said.

Subsequent research, the astronomers say, is needed in part because their computer modeling was done in a “single-column, clear-sky model,” or a one-dimensional measure averaged around a planetary sphere that does not account for the atmospheric effect of clouds.

The findings apply to planet Earth as well. As the sun increases in brightness over time, Earth, too, will move into the runaway greenhouse stage — but not for a billion and a half years or so. Still, it inspired the astronomers to write, “As the solar constant increases with time, Earth’s future is analogous to Venus’s past.”

Source : University of Washington 

By Science & Universe

Violent Sun

Human spaceflight and operations image of the week

Image << SWAP sees the Sun

The SWAP instrument on board ESA's Proba-2 sees the Sun, 30 July 2013, at 9:28:57.258 CEST. SWAP (Sun Watcher using Active Pixel System detector and Image Processing) is a small telescope that captures the solar corona at wavelengths corresponding to temperatures of about a million degrees (around 17.1 nanometers).

Credits: ESA/SWAP PROBA2 science centre

ESA’s Sun-watching Proba-2 satellite has been in orbit since November 2009, demonstrating a range of technologies and serving as a platform for scientific observations.

The 130-kg satellite carries two solar monitors. One is SWAP (Sun Watcher using Active Pixel System detector and Image Processing), a small telescope that captures the solar corona at wavelengths corresponding to temperatures of about a million degrees. The image above shows the latest SWAP image, from 30 July.

SWAP images are used to study the origin of solar phenomena, including solar flares and coronal mass ejections – massive eruptions of material into interplanetary space. Both are important sources of space weather, which profoundly affects the environmental conditions in Earth’s magnetosphere, ionosphere and thermosphere.

Space weather is not only of academic interest. In Europe’s economy today, numerous sectors are potentially affected by space weather, ranging from space-based telecommunications, broadcasting, weather services and navigation through to power distribution and terrestrial communications, especially at northern latitudes.

The satellite has been managed since 1 July by ESA’s Space Situational Awareness (SSA) programme, complementing support provided by ESA’s Science directorate for the Proba-2 Science Centre at the Royal Observatory Belgium.

Proba-2 data are used directly by the SSA Space Weather Coordination Centre at SpacePole, Brussels, to generate space weather products and services for a growing number of customers such as satellite operators, telecom and navigation users, and government agencies and research institutes.

Credits: ESA/SWAP PROBA2 science centre

Two Moons Passing in the Night

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The Saturn moons Mimas and Pandora remind us of how different they are when they appear together, as in this image taken by NASA's Cassini spacecraft. Pandora's small size means that it lacks sufficient gravity to pull itself into a round shape like its larger sibling, Mimas. Researchers believe that the elongated shape of Pandora (50 miles, or 81 kilometers across) may hold clues to how it and other moons near Saturn's rings formed.

This view looks toward the anti-Saturn hemisphere of Mimas (246 miles, or 396 kilometers across). North on Mimas is up and rotated 28 degrees to the right. The image was taken in blue light with Cassini's narrow-angle camera on May 14, 2013. The view was acquired at a distance of approximately 690,000 miles (1.1 million kilometers) from Mimas. Image scale is 4 miles (7 kilometers) per pixel. Pandora was at a distance of 731,000 miles (1.2 million kilometers) when this image was taken. Image scale on Pandora is 4 miles (7 kilometers) per pixel.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colo.

Image Credit: NASA/JPL-Caltech/Space Science Institute

New research indicates that Social monogamy evolved as a result of competition for females.

The socially monogamous dik-dik, a small antelope that lives in Africa. (Credit: Peter Brotherton)

Social monogamy, where one breeding female and one breeding male are closely associated with each other over several breeding seasons, appears to have evolved as a mating strategy, new research reveals. It was previously suspected that social monogamy resulted from a need for extra parental care by the father.

The comparative study, by University of Cambridge researchers Dieter Lukas and Tim Clutton-Brock, shows that the ancestral system for all mammalian groups is of females living in separate ranges with males defending overlapping territories, and that monogamy evolved where males were unable to monopolise and defend multiple females. The research is published in the journal Science.

For the study, the researchers classified all 2500 mammalian species for which information exists as either solitary, socially monogamous or group-living (several breeding females share a common range and either eat or sleep together). They showed that nine per cent of mammals are socially monogamous, including a few rodents, a number of primates, and some carnivores, like jackals, wolves, and meerkats. 

Previously, it had been suggested that monogamy evolved as a result of selection for paternal support in raising offspring (for example, if the female alone could not provide enough food or adequately defend the young). This study shows that paternal care usually evolved after monogamy was already present.

This advance in understanding was, says Lukas of Cambridge's Department of Zoology, due to the volume of information they collected and the availability of genetic information that allowed the researchers to determine the sequence in which different traits evolved.

"Up until now, there have been different ideas about how social monogamy in mammals evolved," says Lukas. "With this study we were able to test all these different hypotheses at once. Paternal care evolves after monogamy is present, and seems to be a consequence rather than a cause of the evolution of monogamy. It appears to occur in about half of all socially monogamous species, and once it does evolve, it provides a clear benefit to the female."

They found convincing support for the hypothesis that monogamy arose as a mating strategy where males could not defend access to more than one female. Monogamy is associated with low density of females, low levels of home-range overlap, and indirectly, with their diets. The study showed that monogamy evolves in species that rely on high quality but patchily distributed food sources, such as meat and fruit. In contrast, in herbivores, which rely on more abundant resources, social monogamy is rare.

"Where females are widely dispersed," says Clutton-Brock, "the best strategy for a male is to stick with one female, defend her, and make sure that he sires all her offspring. In short, a male's best strategy is to be monogamous."

The analysis did not include humans, and the researchers are sceptical that these results tell us much about the evolution of human breeding systems.

Clutton-Brock adds: "It is debatable whether humans should be classified as monogamous. Because all the African apes are polygamous and group living, it is likely that the common ancestor of hominids was also polygamous. One possibility is that the shift to monogamy in humans may be the result in the change of dietary patterns that reduce female density, and another is that slow development of juveniles required extended care by both sexes. However, reliance by humans on cultural adaptations means that it is difficult to extrapolate from ecological relationships in other animals."

Source : University of Cambridge

By Science and Universe

Social Amoebae Travel With a Posse: Tiny Single-Celled Organisms Have Amazingly Complicated Social Lives

The social amoeba called Dictyostelium discoideum, picks up edible bacteria, carries them to new locations and harvests them like crops. (Credit: Joan Strassmann)

In 2011, Nature announced that scientists had discovered a single-celled organism that is a primitive farmer. The organism, a social amoeba called Dictyostelium discoideum, picks up edible bacteria, carries them to new locations and harvests them like crops.

D. discoideum enjoyed a brief spell in the media spotlight, billed as the world's smallest farmer.

Now a collaboration of scientists at Washington University in St. Louis and Harvard University has taken a closer look at one lineage, or clone, of a D. discoideum farmer.

This farmer carries not one but two strains of bacteria. One strain is the "seed corn" for a crop of edible bacteria, and the other strain is a weapon that produces defensive chemicals.

The edible bacteria, the scientists found, evolved from the toxic one. The two strains differ by many mutations but a single key mutation, which hit an important controller in the genome of the nonfood strain, alters expression of 10 percent of its genome. This alteration increases the expression of some genes and decreases the expression of others.

A mutation that affects this much of a genome could be lethal, but in this case it had the surprising effect of making the bacterium edible by changing its chemical profile.

The discovery is reported in the July 29 issue of the Proceedings of the National Academy of Sciences.

The first farmer

The first farmers were found by Debra Brock, then a graduate student in the laboratory run by David Queller and Joan Strassmann at Rice University in Houston, Texas. (All three scientists have since moved to Washington University in St. Louis, where Queller and Strassmann are professors of biology and Brock is a research scientist.)

Brock, who had worked for years with the standard axenic (pure, or uncontaminated) lab clone, noticed something strange about the D. discoideum in the Queller/Strassmann lab, which had been collected from the wild.

When she looked at wild D. discoideum clones under a microscope, she saw bacteria in the sori of some clones. Oddly it was always the same clones that carried bacteria. The bacteria caught her attention because she had never seen anything like this in the lab clone.

"As I tell the students, it's all about the details," Brock says.

A fancy farmer

Whenever she found a D. discoideum clone carrying bacteria, Brock tried to isolate the bacteria. This was a bit hit or miss, she explains, because many organisms that live in the soil cannot be grown in the lab.

Eventually she found a champion D. discoideum: a farmer clone from which she was able to isolate two strains of bacteria. At least the strains looked different when they were cultured in a dish.

She sent the two bacteria out to be identified genetically and both came back as Pseudomonas fluorescens: the same species, even though they were morphologically so different.

"It was a bit of a puzzle," Brock said. On top of that one of the two morphs was edible and the other was not, and the edible one was the first edible strain she had isolated that wasn't a lab feedstock.

"So, I now had two bacteria that seemed the same and one was a food and the other wasn't," Brock said. "That was really odd.."

Toting guns and butter

When the farmer paper appeared in Nature, Jon Clardy of the Harvard Medical School in Boston noticed a passing reference to the D. discoideum farmer with two hitchhikers in the supplement section of the paper. Clardy, who studies the chemistry of mutualism, contacted the Queller/Strassmann lab to suggest the two labs collaborate to unravel the interactions among the newly discovered threesome.

Brock sent the bacteria to Harvard, where Pierre Stallforth, a postdoctoral associate in the Clardy lab, grew them in liquid media. He sent extracts from the media back to Brock, who tested them on D. discoideum to see if they were active.

"Ultimately Pierre figured out that the nonfood strain was producing two chemicals: chromene and pyrrolnitrin. And excitingly, chromene is a new compound," Strassmann said.

"We determined chromene increases spore production in the farmer strain and suppresses spore formation in the nonfarmer strain," she explained. "We saw the same increases in the farmer and decreases in the non-farmer with pyrrolnitrin. A known antibiotic and antifungal, pyrrolnitrin probably also suppresses other organisms in the soil that might compete with the farmer strain."

Assays showed that it was not merely the absence of chromene and pyrrolnitrin that made the food bacterium edible. Something else is going on as well.

Why become butter?

Stallforth next sequenced the entire genome of the two bacterial strains to look for mutations that might explain the differences between them.

The genes responsible for producing pyrrolnitrin were intact in both strains. So he looked at the genes for a two-part global activator that regulates the pyrrolnitrin pathway, among many other genes.

Sure enough, there was a mutation in one of the controller genes of the food bacterium that turned it off and broke the controller. As shown by others in a previous study, breaking the controller changed the expression of 10 percent of the bacteria's genome.

"That's pretty cool, but then you still don't really know for sure if that mutation is the one that matters," Strassmann said.

To check, Stallforth artificially broke the controller -- and only the controller -- in the nonedible P. fluorescens bacterium. The knockout strain he created had the same chemical profile as the food bacterium and it, too, was edible.

Had a similar mutation in the evolutionary past created the edible strain? To answer that question, the scientists constructed a family tree of P. fluorescens clones in the Strassmann/Queller lab by comparing 20 genes.

"It turns out that of all the bacteria strains we've ever isolated, the two we collected from the D. discoideum farmer clone Brock discovered are the most closely related, Queller said.

"The tree also tells us that edibility is a derived trait. These guys used to be inedible and became edible. That's just a weird thing to evolve: to be able to eaten," Queller said.

It makes sense only because it benefits kin, more of whom will be carried to new locations by the well-fed farmer D. discoideumclone, the scientists said.

It's altruism, ultimately. Altruism in miniature
.

Source : Washington University in St. Louis.

By Science and Universe

A Surprisingly Bright Superbubble

This composite image shows a superbubble in the Large Magellanic Cloud (LMC), a small satellite galaxy of the Milky Way located about 160,000 light years from Earth. Many new stars, some of them very massive, are forming in the star cluster NGC 1929, which is embedded in the nebula N44, so named because it is the 44th nebula in a catalog of such objects in the Magellanic Clouds. The massive stars produce intense radiation, expel matter at high speeds, and race through their evolution to explode as supernovas. The winds and supernova shock waves carve out huge cavities called superbubbles in the surrounding gas. X-rays from NASA's Chandra X-ray Observatory (blue) show hot regions created by these winds and shocks, while infrared data from NASA's Spitzer Space Telescope (red) outline where the dust and cooler gas are found. The optical light from the 2.2-m Max-Planck-ESO telescope (yellow) in Chile shows where ultraviolet radiation from hot, young stars is causing gas in the nebula to glow.

A long-running problem in high-energy astrophysics has been that some superbubbles in the LMC, including N44, give off a lot more X-rays than expected from models of their structure. These models assume that hot, X-ray emitting gas has been produced by winds from massive stars and the remains of several supernovas. A Chandra study published in 2011 showed that there are two extra sources of N44's X-ray emission not included in these models: supernova shock waves striking the walls of the cavities, and hot material evaporating from the cavity walls. The Chandra observations also show no evidence for an enhancement of elements heavier than hydrogen and helium in the cavities, thus ruling out this possibility as a third explanation for the bright X-ray emission. Only with long observations making full use of the capabilities of Chandra has it now become possible to distinguish between different sources of the X-rays produced by superbubbles.

Image credit: X-ray: NASA/CXC/U.Mich./S.Oey, IR: NASA/JPL, 

Optical: ESO/WFI/2.2-m

X-rays From A Young Supernova Remnant

More than fifty years ago, a supernova was discovered in M83, a spiral galaxy about 15 million light years from Earth. Astronomers have used NASA's Chandra X-ray Observatory to make the first detection of X-rays emitted by the debris from this explosion.

Named SN 1957D because it was the fourth supernova to be discovered in the year 1957, it is one of only a few located outside of the Milky Way galaxy that is detectable, in both radio and optical wavelengths, decades after its explosion was observed. In 1981, astronomers saw the remnant of the exploded star in radio waves, and then in 1987 they detected the remnant at optical wavelengths, years after the light from the explosion itself became undetectable.

A relatively short observation - about 14 hours long - from NASA's Chandra X-ray Observatory in 2000 and 2001 did not detect any X-rays from the remnant of SN 1957D. However, a much longer observation obtained in 2010 and 2011, totaling nearly 8 and 1/2 days of Chandra time, did reveal the presence of X-ray emission. The X-ray brightness in 2000 and 2001 was about the same as or lower than in this deep image.

This new Chandra image of M83 is one of the deepest X-ray observations ever made of a spiral galaxy beyond our own. This full-field view of the spiral galaxy shows the low, medium, and high-energy X-rays observed by Chandra in red, green, and blue respectively.

The new X-ray data from the remnant of SN 1957D provide important information about the nature of this explosion that astronomers think happened when a massive star ran out of fuel and collapsed. The distribution of X-rays with energy suggests that SN 1957D contains a neutron star, a rapidly spinning, dense star formed when the core of pre-supernova star collapsed. This neutron star, or pulsar, may be producing a cocoon of charged particles moving at close to the speed of light known as a pulsar wind nebula.

If this interpretation is confirmed, the pulsar in SN 1957D is observed at an age of 55 years, one of the youngest pulsars ever seen. The remnant of SN 1979C in the galaxy M100 contains another candidate for the youngest pulsar, but astronomers are still unsure whether there is a black hole or a pulsar at the center of SN 1979C.

Image Credits: X-ray: NASA/CXC/STScI/K.Long et al., Optical: NASA/STScI

By Science and Universe

Exoplanet HD 189733b

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This graphic depicts HD 189733b, the first exoplanet caught passing in front of its parent star in X-rays. As described in NASA's press release , NASA’s Chandra X-ray Observatory and the European Space Agency’s XMM Newton Observatory have been used to observe a dip in X-ray intensity as HD 189733b transits its parent star.

The main figure is an artist’s impression showing the HD 189733 system, containing a Sun-like star orbited by HD 189733b, an exoplanet about the size of Jupiter. This “hot Jupiter” is over 30 times closer to its star than Earth is to the Sun and goes around the star once every 2.2 days, as determined from previous observations. Also in the illustration is a faint red companion star, which was detected for the first time in X-rays with these observations. This star orbits the main star about once every 3,200 years. 

The inset contains the Chandra image of HD 189733. The source in the middle is the main star and the source in the lower right is the faint companion star.  The source at the bottom of the image is a background object not contained in the HD 189733 system.

The exoplanet itself cannot be seen in the Chandra image, as the transits involve measuring small decreases in X-ray emission from the main star. The authors estimate that the percentage decrease in X-ray light during the transits is about three times greater than the corresponding decrease in optical light. This tells them that the region blocking X-rays from the star is substantially larger than the region blocking optical light from the star, helping to determine the size of the planet's atmosphere. The extended atmosphere implied by these results is shown by the light blue color around the planet. Recent observations of HD 189733b with the Hubble Space Telescope have confirmed that the lower atmosphere of the planet has a deep blue color, due to the preferential scattering of blue light by silicate particles in its atmosphere.

For about a decade astronomers have known that ultraviolet and X-ray radiation from the main star in HD 189733 are evaporating the atmosphere of its closely orbiting planet over time. The authors of the new study estimate that HD 189733b is losing between 100 million and 600 million kilograms per second. This rate is about 25% to 65% higher than it would be if the planet's atmosphere were not extended.

At a distance of just 63 light years, HD 189733b is the closest hot Jupiter to Earth, which makes it a prime target for astronomers who want to learn more about this type of exoplanet and the atmosphere around it.

Chandra was used to make observations of six transits by HD 189733b and the team also used archival data from XMM-Newton for one transit. These results are available online and will appear in the August 10th issue of The Astrophysical Journal. 

Credit: X-ray: NASA/CXC/SAO/K. Poppenhaeger et al; Illustration: NASA/CXC/M. Weiss

By Science and Universe

Laser communications set for Moon mission

<< Image : ESA's Optical Ground Station (OGS) is 2400 m above sea level on the volcanic island of Tenerife. Visible green laser beams are used for stabilising the sending and receiving telescopes on the two islands. The invisible infrared single photons used for quantum teleportation are sent from the neighbouring island La Palma and received by the 1 m Telescope located under the dome of the OGS. Initial experiments with entangled photons were performed in 2007, but teleportation of quantum states could only be achieved in 2012 by improving the performance of the set-up. Aside from inter-island experiments for quantum communication and teleportation, the OGS is also used for standard laser communication with satellites, for observations of space debris or for finding new asteroids. The picture is a multiple exposure also including Tenerife's Teide volcano and the Milky Way in the background. 

An advanced laser system offering vastly faster data speeds is now ready for linking with spacecraft beyond our planet following a series of crucial ground tests. Later this year, ESA’s observatory in Spain will use the laser to communicate with a NASA Moon orbiter.

The laboratory testing paves the way for a live space demonstration in October, once NASA’s Lunar Atmosphere and Dust Environment Explorer – LADEE – begins orbiting the Moon.

LADEE carries a terminal that can transmit and receive pulses of laser light. ESA’s Optical Ground Station on Tenerife will be upgraded with a complementary unit and, together with two US ground terminals, will relay data at unprecedented rates using infrared light beams at a wavelength similar to that used in fiber-optic cables on Earth.

“The testing went as planned, and while we identified a number of issues, we’ll be ready for LADEE’s mid-September launch,” says Zoran Sodnik, manager for ESA’s Lunar Optical Communication Link project.

LADEE approaching lunar orbit

“Our ground station will join two NASA stations communicating with the LADEE Moon mission, and we aim to demonstrate the readiness of optical communication for future missions to Mars or anywhere else in the Solar System.”

Testing new European technology

The testing took place in July at a Zurich, Switzerland, facility owned by ESA’s industrial partner RUAG and made use of a new detector and decoding system, a ranging system and a transmitter.

A NASA team, supported by the Massachusetts Institute of Technology, Lincoln Laboratory and the Jet Propulsion Laboratory, brought over their laser terminal simulator, while ESA together with RUAG and Axcon of Denmark set up the European equipment to test compatibility between the two sets of hardware.

“This interagency optical compatibility test was the first of its kind, and it established the uplink, downlink and the ranging measurement,” says ESA’s Klaus-Juergen Schulz, responsible for ground station systems at the European Space Operations Centre, Darmstadt. 

The first laser link-up with LADEE is expected to be attempted four weeks after launch, around mid-October.

Laser pathways to future space communication

Laser communications at near-infrared wavelengths may be the way of the future when it comes to downloading massive amounts of data from spacecraft orbiting Earth, Mars or even more distant planets.

These units are lighter, smaller and need less power than today’s radio systems, promising to cut mission costs and provide opportunities for new science payloads.

In addition, ESA has also developing satellite-to-satellite laser communications for its Alphasat and European Data Relay System missions .

Source : ESA

By Science and Universe

Migraines Associated With Variations in Structure of Brain Arteries

The network of arteries supplying blood flow to the brain is more likely to be incomplete in people who suffer migraine, a new study by researchers in the Perelman School of Medicine at the University of Pennsylvania reports. Variations in arterial anatomy lead to asymmetries in cerebral blood flow that might contribute to the process triggering migraines. The image depicts the anatomy of the circle of Willis (A) and representative subjects with a complete (B) and incomplete circle of Willis (C). The arrowhead indicates absent anterior communicating artery and arrows indicate bilateral absent posterior communicating arteries. Abbreviations are defined as ICA: internal carotid artery; ACA: anterior cerebral artery; MCA: middle cerebral artery; PCA; posterior cerebral artery; BA: basilar artery; VA: vertebral artery; Acomm: anterior communicating artery; Pcomm: posterior communicating artery; A1, A2, P1, P2: branches of the anterior and posterior cerebral arteries. The vertebral arteries are not normally considered part of the circle of Willis, but are important to the intracranial arterial supply. (Credit: Penn Medicine/Brett Cucchiara, MD, and John Detre, MD)

The network of arteries supplying blood flow to the brain is more likely to be incomplete in people who suffer migraine, a new study by researchers in the Perelman School of Medicine at the University of Pennsylvania reports. Variations in arterial anatomy lead to asymmetries in cerebral blood flow that might contribute to the process triggering migraines.The arterial supply of blood to the brain is protected by a series of connections between the major arteries, termed the "circle of Willis" after the English physician who first described it in the 17th century. People with migraine, particularly migraine with aura, are more likely to be missing components of the circle of Willis.

Migraine affects an estimated 28 million Americans, causing significant disability. Experts once believed that migraine was caused by dilation of blood vessels in the head, while more recently it has been attributed to abnormal neuronal signals. In this study, appearing in PLOS ONE, researchers suggest that blood vessels play a different role than previously suspected: structural alterations of the blood supply to the brain may increase susceptibility to changes in cerebral blood flow, contributing to the abnormal neuronal activity that starts migraine.

"People with migraine actually have differences in the structure of their blood vessels -- this is something you are born with," said the study's lead author, Brett Cucchiara, MD, Associate Professor of Neurology. "These differences seem to be associated with changes in blood flow in the brain, and it's possible that these changes may trigger migraine, which may explain why some people, for instance, notice that dehydration triggers their headaches."

In a study of 170 people from three groups -- a control group with no headaches, those who had migraine with aura, and those who had migraine without aura -- the team found that an incomplete circle of Willis was more common in people with migraine with aura (73 percent) and migraine without aura (67 percent), compared to a headache-free control group (51 percent). The team used magnetic resonance angiography to examine blood vessel structure and a noninvasive magnetic resonance imaging method pioneered at the University of Pennsylvania, called Arterial spin labeling (ASL), to measure changes in cerebral blood flow.

"Abnormalities in both the circle of Willis and blood flow were most prominent in the back of the brain, where the visual cortex is located. This may help explain why the most common migraine auras consist of visual symptoms such as seeing distortions, spots, or wavy lines," said the study's senior author, John Detre, MD, Professor of Neurology and Radiology.

Both migraine and incomplete circle of Willis are common, and the observed association is likely one of many factors that contribute to migraine in any individual. The researchers suggest that at some point diagnostic tests of circle of Willis integrity and function could help pinpoint this contributing factor in an individual patient. Treatment strategies might then be personalized and tested in specific subgroups.

Source :  University of Pennsylvania School of Medicine.
By Science and Universe

Near-Earth Asteroid 2003 DZ15 to Pass Earth Monday Night

The current orbital position of asteroid 2003 DZ15. (Created by the author using JPL’s Small-Body Database Browser).

The Earth will get another close shave Monday, when the 152 metre asteroid 2003 DZ15 makes a pass by our fair planet on the night of July 29^th/30^th at 3.5 million kilometres distant.  This is over 9 times the Earth-Moon distance and poses no threat to our world.

This is much smaller than 2.75 kilometre 1998 QE2, which sailed by (bad pun intended) our fair world at 5.8 million kilometres distant on May 31st, 2013. The Virtual Telescope Project will be presenting a free online event to monitor the passage of NEA 2003 DZ15 starting Monday night July 29^th at 22:00 UT/6:00 PM EDT.

Radio astronomer Alessondra Springmann told Universe Todaythat, “2003 DZ15 is a little to small and a little too far away for the Arecibo Observatory to detect during this apparition.” No other efforts are currently known of by professional observatories to monitor its passage via radar.

An Apollo asteroid, 2003 DZ15 was confirmed by the Lowell Observatory and NEAT’s Mount Palomar telescope upon discovery in February 2003. This is its closest approach to the Earth for this century, although it will make a pass nearly as close to the Earth in 2057 on February 12^th.

With a perihelion (closest approach to the Sun of) 0.63 A.U.s, 2003 DZ15 can also makeclose passes by the planet Venus as well, which it last did in 1988 and will do again on 2056.

Closest approach of 2003 DZ15 is set for 00:37 UT July 30^th, or 8:37 PM EDT the evening of Monday, July 29^th. Although it will only reach about +14th magnitude (based on an absolute magnitude of +22.2), and hence be out of range to all but the very largest Earthbound backyard telescopes, it’ll be fun to watch as it slowly drifts across the starry background live on the internet. Our own, “is worth tracking down from our own backyard” limit is an asteroid passing closer than our Moon, or is farther, but is brighter than +10^th magnitude… such are the limitations of humid Florida skies!

Watch the video how the asteroid will pass

Of course, an asteroid the size of 2003 DZ15 would spell a bad day for the Earth, were it headed our way. At an estimated 152 metres in size, 2003 DZ is over seven times the size of the Chelyabinsk meteor that exploded over Russia the day after Valentine ’s on February 15^th of this year. While not in the class of an Extinction Level event, 2003 DZ15 would be in 60 to 190 metre size of range of the Tunguska impactor that struck Siberia in 1908.

All enough for us to take notice as 2003 DZ15 whizzes by, at a safe distance this time. NASA plans to launch a crewed mission sometime over the next decade to study an asteroid, and  perhaps retrieve a small NEA and place it in orbit about Earth’s Moon. Such efforts may go a long way in understanding and dealing with such potentially hazardous space rocks, when and if the “big one” is discovered heading our way. We’re the Earth’s first line of defense- and unlike the ill-fated dinosaurs, WE’VE got a space program and can do something about it!

Source : Universe Today