Sunday, 30 November 2014

DNA's Ability to Survive Extreme Conditions of Space --"Has Implications in Search for Extraterrestrial Life"


DNA can survive a flight through space and re-entry into Earth’s atmosphere — and still pass on genetic information. A team of scientists from the University of Zurich obtained these astonishing results during an experiment on the TEXUS-49 research rocket mission. Various scientists believe that DNA could certainly reach us from outer space as Earth is not insulated: in extraterrestrial material made of dust and meteorites, for instance, around 100 tons of which hits our planet every day.

“This study provides experimental evidence that the DNA’s genetic information is essentially capable of surviving the extreme conditions of space and the re-entry into Earth’s dense atmosphere,” says study head Oliver Ullrich from the University of Zurich’s Institute of Anatomy.

This extraordinary stability of DNA under space conditions also needs to be factored into the interpretion of results in the search for extraterrestrial life: “The results show that it is by no means unlikely that, despite all the safety precautions, space ships could also carry terrestrial DNA to their landing site. We need to have this under control in the search for extraterrestrial life,” points out Ullrich.

Applied to the outer shell of the payload section of a rocket using pipettes, small, double-stranded DNA molecules flew into space from Earth and back again. After the launch, space flight, re-entry into Earth’s atmosphere and landing, the so-called plasmid DNA molecules were still found on all the application points on the rocket from the TEXUS-49 mission. And this was not the only surprise: For the most part, the DNA salvaged was even still able to transfer genetic information to bacterial and connective tissue cells.

The experiment called DARE (DNA atmospheric re-entry experiment) resulted from a spontaneous idea: UZH scientists Dr. Cora Thiel and Ullrich were conducting experiments on the TEXUS-49 mission to study the role of gravity in the regulation of gene expression in human cells using remote-controlled hardware inside the rocket’s payload. During the mission preparations, they began to wonder whether the outer structure of the rocket might also be suitable for stability tests on so-called biosignatures.

Biosignatures are molecules that can prove the existence of past or present extraterrestrial life,” explains Dr. Thiel. And so the two UZH researchers launched a small second mission at the European rocket station Esrange in Kiruna, north of the Arctic Circle.

The quickly conceived additional experiment was originally supposed to be a pretest to check the stability of biomarkers during spaceflight and re-entry into the atmosphere. Dr. Thiel did not expect the results it produced: “We were completely surprised to find so much intact and functionally active DNA.” The study reveals that genetic information from the DNA can essentially withstand the most extreme conditions..

Two types of biomolecules serve as the genetic information carriers for all Earthly biota. RNA on its own suffices for the business of life for simpler creatures, such as some viruses. Complex life, like humans, however, relies on DNA as its genetic carrier. Extremophiles have been discovered in recent decades thriving in strongly acidic hot springs, within liquid asphalt, and in other eyebrow-raising niches. Salt-tolerant bacteria and archaea, like H. volcanii, have been found to survive in deserts, and simulated Mars conditions. We should not be surprised, perhaps, if life has managed to take hold on formidable worlds.

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Saturday, 29 November 2014

The Hunt for Colossal "Quark" Stars --Do They Exist? (Holiday Weekend Feature)

Recent research suggests that neutron stars may gradually transform into 'strange' stars - i.e. in stars made up primarily from the 'strange' quark. The conventional wisdom is that the electric field of a such a hypothetical strange star (made up from strange matter) at its surface would be so huge and its luminosity so big that it would be impossible to confuse it with anything else.

However, Jaikumar and his fellow researchers from the Argonne National Laboratory, and two colleagues from Los Alamos National Laboratory in New Mexico, have challenged that. The team developed a theory about what a strange star would look like.

One of the most interesting aspects of neutron stars is that they are not gaseous like usual stars, but they are so closely packed that they are liquid. Strange stars should also be liquid with a surface that is solid.

However, Jaikumar and his colleagues challenge that. Strange stars are usually assumed to exhibit huge electric fields on their surface precisely because they are assumed to have a smooth surface. But according to the scientists neither neutron stars nor strange stars have such a smooth solid-like surface.

"It's like taking water," Jaikumar says, "with a flat surface. Add detergent and it reduces surface tension, allowing bubbles to form. In a strange star, the bubbles are made of strange quark matter, and float in a sea of electrons. Consequently, the star's surface may be crusty, not smooth. The effect of surface tension had been overlooked before."

One consequence is that a strange star wouldn't have large electrical field at surface or be super-luminous. It also allows for a strange star to be less dense than originally thought, although such stars are definitely unusually dense compared to regular stars.

Much of the matter in our Universe may be made of a type of dark matter called weakly interacting massive particles, also known as WIMPs. Although some scientists predict that these hypothetical particles possess many of the necessary properties to account for dark matter, until recently scientists have not been able to make any definite predictions of their mass. In a new study, physicists have derived a limit on the WIMP mass by calculating how these dark matter particles can transform neutron stars into stars made of strange quark matter, or "strange" stars.

WIMPs are thought to be largely located in the halos of galaxies. Although galaxy halos (image above) are not visible, they contain most of a galaxy's mass in the form of the heavy WIMPs.

Dr. M. Angeles Perez-Garcia from the University of Salamanca in Salamanca, Spain, along with Dr. Joseph Silk of the University of Oxford and Dr. Jirina R. Stone of the University of Oxford and the University of Tennessee showed that, when a neutron star gravitationally captures nearby WIMPs, the WIMPs may trigger the conversion of the neutron star into a strange star.

One important issue is whether at high density 'strange' quark matter is more stable than regular matter (which is comprised of 'up' and 'down' quarks). Jaikumar and colleagues think that as a neutron star spins down and its core density increases, it may convert into the more stable state of strange quark matter, forming a strange star.

Theorists cannot say with absolute certainty whether or not a neutron star gradually converts into a strange star. The conversion occurs, according to new research, as a result of the WIMPs seeding the neutron stars with long-lived lumps of strange quark matter, or strangelets. WIMPs captured in the neutron star's core self-annihilate, releasing energy in the process.

According to Jaikumar, making the distinction is rather tricky: "There might be a slight difference. You'd look at surface temperature and see how stars are cooling in time. If it is quark matter, the emission rates are different, so the strange star may cool a little faster."

It's the astronomers' job to discover whether strange stars exist or not. Either discovery will have important implications for the theory of Quantum Chromodynamics (QCD) -- which is the fundamental theory of quarks. "Finding a strange star would improve our understanding of QCD, the fundamental theory of the nuclear force. And it would also be the first solid evidence of stable quark matter", Jaikumar said.

Elsewhere, Kwong-Sang Cheng of the University of Hong Kong, China, and colleagues have presented evidence that a quark star formed in a bright supernova called SN 1987A (above), which is among the nearest supernovae to have been observed.

Observing a quark star could shed light on what happened just after the Big Bang, because at this time, the Universe was filled with a dense sea of quark matter superheated to a trillion °C. While some groups have claimed to have found candidate quark stars, no discovery has yet been confirmed.

Now Kwong-Sang Cheng of the University of Hong Kong, China, and colleagues have presented evidence that a quark star formed in a bright supernova called SN 1987A (pictured), which is among the nearest supernovae to have been observed.

The birth of a neutron star is known to be accompanied by a single burst of neutrinos. But when the team examined data from two neutrino detectors - Kamiokande II in Japan and Irvine-Michigan-Brookhaven in the US - they found that SN 1987A gave off two separate bursts.

"There is a significant time delay between [the bursts recorded by] these two detectors," says Cheng. They believe the first burst was released when a neutron star formed, while the second was triggered seconds later by its collapse into a quark star. The results appeared in The Astrophysical Journal (

"This model is intriguing and reasonable," says Yong-Feng Huang of Nanjing University, China. "It can explain many key features of SN 1987A." However, Edward Witten of the Institute for Advanced Study in Princeton, New Jersey, is not convinced. "I hope they're right," he says. "My first reaction, though, is that this is a bit of a long shot."

High-resolution X-ray observatories, due to fly in space in the next decade, may have the final say. Neutron stars and quark stars should look very different at X-ray wavelengths, says Cheng.

The image of SN 1987A at top of the page combines data from NASA's orbiting Chandra X-ray Observatory and the 8-meter Gemini South infrared telescope in Chile, which is funded primarily by the National Science Foundation.

The X-ray light detected by Chandra is colored blue. The infrared light detected by Gemini South is shown as green and red, marking regions of slightly higher and lower-energy infrared, respectively. The core remains of the star that exploded in 1987 is not visible here. The ring is produced by hot gas (largely the X-ray light) and cold dust (largely the infrared light) from the exploded star interacting with the interstellar region. Credit: Gemini/NASA

"Supernova 1987A is changing right before our eyes," said Dr. Eli Dwek, a cosmic dust expert at NASA Goddard Space Flight Center in Greenbelt, Md. For several years Dwek has been following this supernova, named 1987A for the year it was discovered in the Large Magellanic Cloud, a neighboring dwarf galaxy. "What we are seeing now is a milestone in the evolution of a supernova."

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Friday, 28 November 2014

"Life is a Space Voyage" --Kurt Vonnegut (A 'Galaxy' Insight)


"I love you sons of bitches. You're all I read any more. You're the only ones who'll talk all about the really terrific changes going on, the only ones crazy enough to know that life is a space voyage, and not a short one, either, but one that'll last for billions of years. You're the only ones with guts enough to really care about the future, who really notice what machines do to us, what wars do to us, what cities do to us, what big, simple ideas do to what tremendous misunderstanding, mistakes, accidents, catastrophes do to us. You're the only ones zany enough to agonize over time and distance without limit, over mysteries that will never die, over the fact that we are right now determining whether the space voyage for the next billion years or so is going to be Heaven or Hell."

Spoken by Eliot Rosewater to a group of science fiction writers in Vonnegut's underrated masterpiece, God Bless You Mr. Rosewater.

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Thursday, 27 November 2014

Asteroid Impact 3.3 Billion Years Ago "Dwarfed the Dinosaur-Extinction Event" (Thanksgiving Holiday Feature)

Although scientists had previously hypothesized enormous ancient impacts, much greater than the one that may have eliminated the dinosaurs, a 2014 study revealed the power and scale of a cataclysmic event which is thought to have created geological features found in a South African region known as the Barberton greenstone belt.

Reconstructing the asteroid’s impact could help scientists better understand the conditions under which early life on the planet evolved. Along with altering the Earth itself, the environmental changes triggered by the impact may have wiped out many microscopic organisms living on the developing planet, allowing other organisms to evolve, they said.

The collision punched a crater into the planet’s crust that’s nearly 500 kilometers (about 300 miles) across: greater than the distance from Washington, D.C. to New York City, and up to two and a half times larger in diameter than the hole formed by the dinosaur-killing asteroid 65 million years ago. Seismic waves bigger than any recorded earthquakes shook the planet for about half an hour at any one location – about six times longer than the huge earthquake that struck Japan three years ago. The impact also sets off tsunamis many times deeper than the one that followed the Japanese quake.


The huge impactor – between 37 and 58 kilometers (23 to 36 miles) wide – collided with the planet at 20 kilometers per second (12 miles per second). The jolt, bigger than a 10.8 magnitude earthquake, propelled seismic waves hundreds of kilometers through the Earth, breaking rocks and setting off other large earthquakes. Tsunamis thousands of meters deep – far bigger than recent tsunamis generated by earthquakes — swept across the oceans that covered most of the Earth at that time.

A graphical representation of the size of the asteroid thought to have killed the dinosaurs, and the crater it created, compared to an asteroid thought to have hit the Earth 3.26 billion years ago and the size of the crater it may have generated. A new study reveals the power and scale of the event some 3.26 billion years ago which scientists think created geological features found in a South African region known as the Barberton greenstone belt.

A graphical representation of the size of the asteroid thought to have killed the dinosaurs, and the crater it created, compared to an asteroid thought to have hit the Earth 3.26 billion years ago and the size of the crater it may have generated. A new study reveals the power and scale of the event some 3.26 billion years ago which scientists think created geological features found in a South African region known as the Barberton greenstone belt.

Lowe, who discovered telltale rock formations in the Barberton greenstone a decade ago, thought their structure smacked of an asteroid impact. The new research models for the first time how big the asteroid was and the effect it had on the planet, including the possible initiation of a more modern plate tectonic system that is seen in the region, according to Lowe.

The study marks the first time scientists have mapped in this way an impact that occurred more than 3 billion years ago, Lowe added, and is likely one of the first times anyone has modeled any impact that occurred during this period of the Earth’s evolution.

The impact would have been catastrophic to the surface environment. The smaller, dino-killing asteroid crash is estimated to have released more than a billion times more energy than the bombs that destroyed Hiroshima and Nagasaki. The more ancient hit now coming to light would have released much more energy, experts said.

The sky would have become red hot, the atmosphere would have been filled with dust and the tops of oceans would have boiled, the researchers said. The impact sent vaporized rock into the atmosphere, which encircled the globe and condensed into liquid droplets before solidifying and falling to the surface, according to the researchers.

The impact may have been one of dozens of huge asteroids that scientists think hit the Earth during the tail end of the Late Heavy Bombardment period, a major period of impacts that occurred early in the Earth’s history – around 3 billion to 4 billion years ago.

Many of the sites where these asteroids landed were destroyed by erosion, movement of the Earth’s crust and other forces as the Earth evolved, but geologists have found a handful of areas in South Africa, and Western Australia that still harbor evidence of these impacts that occurred between 3.23 billion and 3.47 billion years ago. The study’s co-authors think the asteroid hit the Earth thousands of kilometers away from the Barberton Greenstone Belt, although they can’t pinpoint the exact location.

“We can’t go to the impact sites. In order to better understand how big it was and its effect we need studies like this,” said Lowe. Scientists must use the geological evidence of these impacts to piece together what happened to the Earth during this time, he said.

The study’s findings have important implications for understanding the early Earth and how the planet formed. The impact may have disrupted the Earth’s crust and the tectonic regime that characterized the early planet, leading to the start of a more modern plate tectonic system, according to the paper’s co-authors.

The pummeling the planet endured was “much larger than any ordinary earthquake,” said Norman Sleep, a physicist at Stanford University and co-author of the study. He used physics, models, and knowledge about the formations in the Barberton greenstone belt, other earthquakes and other asteroid impact sites on the Earth and the moon to calculate the strength and duration of the shaking that the asteroid produced. Using this information, Sleep recreated how waves traveled from the impact site to the Barberton greenstone belt and caused the geological formations.

The geological evidence found in the Barberton that the paper investigates indicates that the asteroid was “far larger than anything in the last billion years,” said Jay Melosh, a professor at Purdue University in West Lafayette, Indiana, who was not involved in the research.

The Barberton greenstone belt is an area 100 kilometers (62 miles) long and 60 kilometers (37 miles) wide that sits east of Johannesburg near the border with Swaziland. It contains some of the oldest rocks on the planet.

The model provides evidence for the rock formations and crustal fractures that scientists have discovered in the Barberton greenstone belt, said Frank Kyte, a geologist at UCLA who was not involved in the study.

“This is providing significant support for the idea that the impact may have been responsible for this major shift in tectonics,” he said.

“We are trying to understand the forces that shaped our planet early in its evolution and the environments in which life evolved,” Lowe said.

No mass extinction on Earth has been so tightly linked to an impact as the Chicxulub Crater which cuts across the northern Yucatan peninsula in Mexico in a mighty arc 170 kilometers (105 miles) across. The crater's size implies an asteroid some 10 kilometers -seven miles- wide and reaching a depth as deep as the deepest ocean trench plunging the Earth into a global winter night that cut off photosynthesis for months, even years.

But one other impact may make the Chicxulub impact look like a 4th of July event. In 2006, NASA gravity and subsurface radar maps revealed a 500-kilometer-wide crater that lies hidden more than a mile beneath the East Antarctic Ice Sheet, created by a 50-kilometer wide object. The gravity measurements suggest that it could date back about 250 million years -- the time of the Permian-Triassic extinction, when almost all animal life on Earth died out.

Its size and location -- in the Wilkes Land region of East Antarctica, south of Australia -- also suggest that it could have begun the breakup of the Gondwana supercontinent by creating the tectonic rift that pushed Australia northward.

Paleontologists believe that the Permian-Triassic extinction paved the way for the dinosaurs to rise to prominence. The Wilkes Land crater is more than twice the size of the Chicxulub crater, which marks the impact that may have ultimately killed the dinosaurs 65 million years ago. The void left at the K-T boundary created by the impact left the world to the mammals.

"This Wilkes Land impact is much bigger than the impact that killed the dinosaurs, and probably would have caused catastrophic damage at the time," said Ralph von Frese, a professor of geological sciences at Ohio State University.

Von Frese and Laramie Potts, a postdoctoral researcher in geological sciences, led the team that discovered the crater. They collaborated with other Ohio State and NASA scientists, as well as international partners from Russia and Korea. They reported their preliminary results in a recent poster session at the American Geophysical Union Joint Assembly meeting in Baltimore.

The scientists used gravity fluctuations measured by NASA's GRACE satellites to peer beneath Antarctica's icy surface, and found a 200-mile-wide plug of mantle material -- a mass concentration, or "mascon" -- that had risen up into the Earth's crust. Mascons form where large objects slam into a planet's surface. Upon impact, the denser mantle layer bounces up into the overlying crust, which holds it in place beneath the crater.

When the scientists overlaid their gravity image with airborne radar images of the ground beneath the ice, they found the mascon perfectly centered inside a circular ridge some 300 miles wide -- a crater easily large enough to hold the state of Ohio.

Taken alone, the ridge structure wouldn't prove anything. But to von Frese, the addition of the mascon means "impact." Years of studying similar impacts on the moon have honed his ability to find them.

"If I saw this same mascon signal on the moon, I'd expect to see a crater around it," he said. "And when we looked at the ice-probing airborne radar, there it was. There are at least 20 impact craters this size or larger on the moon, so it is not surprising to find one here," he continued. "The active geology of the Earth likely scrubbed its surface clean of many more."

He and Potts admitted that such signals are open to interpretation. Even with radar and gravity measurements, scientists are only just beginning to understand what's happening inside the planet. Still, von Frese said that the circumstances of the radar and mascon signals support their interpretation.

"We compared two completely different data sets taken under different conditions, and they matched up," he said.

To estimate when the impact took place, the scientists took a clue from the fact that the mascon is still visible.

"On the moon, you can look at craters, and the mascons are still there," von Frese said. "But on Earth, it's unusual to find mascons, because the planet is geologically active. The interior eventually recovers and the mascon goes away." He cited the very large and much older Vredefort crater in South Africa that must have once had a mascon, but no evidence of it can be seen now.

"Based on what we know about the geologic history of the region, this Wilkes Land mascon formed recently by geologic standards -- probably about 250 million years ago," he said. "In another half a billion years, the Wilkes Land mascon will probably disappear, too."

Approximately 100 million years ago, Australia split from the ancient Gondwana supercontinent and began drifting north, pushed away by the expansion of a rift valley into the eastern Indian Ocean. The rift cuts directly through the crater, so the impact may have helped the rift to form, von Frese said.

"All the environmental changes that would have resulted from the impact would have created a highly caustic environment that was really hard to endure. So it makes sense that a lot of life went extinct at that time," he said.

The ultimate proof of the Antarctica impact theory lies in finding the shattered rock -the stuff of future expeditions and discovery.

What would happen to the human species and life on Earth in general if an asteroid the size of the one that created the famous K/T Event, and impact exponentially smaller than the Wilkes Land impact?

As Stephen Hawking says, the general consensus is that any comet or asteroid greater than 20 kilometers in diameter that strikes the Earth will result in the complete annihilation of complex life - animals and higher plants. (The asteroid Vesta, for example, one of the destinations of the Dawn Mission, is the size of Arizona).

How many times in our galaxy alone has life finally evolved to the equivalent of our planets and animals on some far distant planet, only to be utterly destroyed by an impact? Galactic history suggests it might be a common occurrence.

The first this to understand about the KT event is that is was absolutely enormous: an asteroid (or comet) six to 10 miles in diameter streaked through the Earth's atmosphere at 25,000 miles an hour and struck the Yucatan region of Mexico with the force of 100 megatons -the equivalent of one Hiroshima bomb for every person alive on Earth today. Not a pretty scenario!

Recent calculations show that our planet would go into another "Snowball Earth" event like the one that occurred 600 million years ago, when it is believed the oceans froze over (although some scientists dispute this hypothesis -see link below).

While microbial bacteria might readily survive such calamitous impacts, our new understanding from the record of the Earth's mass extinctions clearly shows that plants and animals are very susceptible to extinction in the wake of an impact.

Impact rates depend on how many comets and asteroids exist in a particular planetary system. In general there is one major impact every million years -a mere blink of the eye in geological time. It also depends on how often those objects are perturbed from safe orbits that parallel the Earth's orbit to new, Earth-crossing orbits that might, sooner or later, result in a catastrophic K/T or Permian-type mass extinction.

The asteroid that hit Vredefort located in the Free State Province of South Africa is one of the largest to ever impact Earth, estimated at over 10 km (6 miles) wide, although it is believed by many that the original size of the impact structure could have been 250 km in diameter, or possibly larger(though the Wilkes Land crater in Antarctica, if confirmed to have been the result of an impact event, is even larger at 500 kilometers across). The town of Vredefort is situated in the crater.

Dating back 2,023 million years, it is the oldest astrobleme found on earth so far, with a radius of 190km, it is also the most deeply eroded. Vredefort Dome Vredefort bears witness to the world’s greatest known single energy release event, which caused devastating global change, including, according to many scientists, major evolutionary changes.

What has kept the Earth "safe" at least the past 65 million years, other than blind luck is the massive gravitational field of Jupiter, our cosmic guardian, with its stable circular orbit far from the sun, which assures a low number of impacts resulting in mass extinctions by sweeping up and scatters away most of the dangerous Earth-orbit-crossing comets and asteroids

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Tuesday, 25 November 2014

"Science of Interstellar" Live-Streamed on Google + Wednesday --Discussion with Three World-Renowned Cosmologists


Interstellar is the latest blockbuster movie about space. Now in a special live Google Hangout, three astrophysicists brush off the popcorn, leave the theater and answer your questions about the “science” in the movie. On Wednesday, November 26, from 3:00 p.m. to 3:30 p.m. EST, Mandeep Gill, Eric Miller and Hardip Sanghera — will separate the science of "Interstellar" from its fiction and answer your questions.

Mandeep Gill, an observational cosmologist at the Kavli Institute for Particle Astrophysics and Cosmology, located at Stanford University and SLAC National Accelerator Laboratory. His research focuses on gravity's bending of light and the mysteries of dark matter and dark energy.

Eric Miller is a research scientist at the MIT Kavli Institute for Astrophysics and Space Research, where he studies diffuse gas to understand the structure of mass and how galaxies interact with their surroundings. He is a member of science and instrument teams for the Chandra and Suzaku X-ray Observatories, with active collaborations in the U.S. and Japan.


Hardip Sanghera is a member of the Cambridge Planck Analysis Centre, based in the Kavli Institute for Cosmology Cambridge.He supports the European Space Agency's space-based Planck observatory, which recently completed mapping the universe's earliest light.

In the opening scenes of Interstellar the Earth is a catastrophic wasteland of dying farms and mile-high dust storms. With just years before facing complete oblivion, humanity needs to find a new planetary home. It’s a “Hail Mary” of a job, and taking it on are four astronauts who must enter a wormhole to find an extremely distant habitable planet suited for a mass exodus.

The movie is already a blockbuster, in part because a lot of thought and attention went into making a film based deep in science and theory. This goes from the look of wormholes to the push-pull of gravity on a planet to the way a black hole might readjust your concept of time. But just how much of the movie is really true to what we know about the universe? And how much of it is, say… creative license?

To find out, Curious Stardust sent three bloggers into the darkness of their neighborhood theaters. And now, on Wednesday, November 26, from 12:00-12:30pm PST, Mandeep Gill, Eric Miller and Hardip Sanghera will separate Interstellar’s science from its fiction. They will also answer your questions in a live Google Hangout.

Submit questions ahead of and during the webcast by emailing or by using the hashtag #KavliSciBlog on Twitter or Google+.

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Monday, 24 November 2014

"The Scaffolding of Our Universe is Being Slowly Swallowed by Dark Energy"


New research offers a novel insight into the nature of dark matter and dark energy and what the future of our Universe might be. Cosmology has undergone a paradigm shift since 1998 when researchers announced that the rate at which the Universe was expanding was accelerating. The idea of a constant dark energy throughout space-time (the “cosmological constant”) became the standard model of cosmology, but now reserachers at the University of Portsmouth and Rome believe they have found a better description, including energy transfer between dark energy and dark matter. They have found hints that dark matter, the cosmic scaffolding on which our Universe is built, is being slowly erased, swallowed up by dark energy.

The findings appear in the journal Physical Review Letters, published by the American Physical Society. In the journal the cosmologists argue that the latest astronomical data favours a dark energy that grows as it interacts with dark matter, and this appears to be slowing the growth of structure in the cosmos.

“This study is about the fundamental properties of space-time," says David Wands, Director of Portsmouth’s Institute of Cosmology and Gravitation. "On a cosmic scale, this is about our Universe and its fate. If the dark energy is growing and dark matter is evaporating we will end up with a big, empty, boring Universe with almost nothing in it. Dark matter provides a framework for structures to grow in the Universe. The galaxies we see are built on that scaffolding and what we are seeing here, in these findings, suggests that dark matter is evaporating, slowing that growth of structure.”

Research students Valentina Salvatelli and Najla Said from the University of Rome worked in Portsmouth with Dr Marco Bruni and Wands, and with Alessandro Melchiorri in Rome. They examined data from a number of astronomical surveys, including the Sloan Digital Sky Survey, and used the growth of structure revealed by these surveys to test different models of dark energy.

Valentina and Najla spent several months here over the summer looking at the consequences of the latest observations. Much more data is available now than was available in 1998 and it appears that the standard model is no longer sufficient to describe all of the data. We think we’ve found a better model of dark energy.

“Since the late 1990s astronomers have been convinced that something is causing the expansion of our Universe to accelerate. The simplest explanation was that empty space – the vacuum – had an energy density that was a cosmological constant. However there is growing evidence that this simple model cannot explain the full range of astronomical data researchers now have access to; in particular the growth of cosmic structure, galaxies and clusters of galaxies, seems to be slower than expected.”

“Any time there is a new development in the dark energy sector we need to take notice since so little is understood about it," observed Dragan Huterer,of the University of Michigan. "I would not say, however, that I am surprised at the results, that they come out different than in the simplest model with no interactions. We’ve known for some months now that there is some problem in all data fitting perfectly to the standard simplest model.”

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Saturday, 22 November 2014

NASA's New View of Jupiter's Ocean Moon --Is Europa the Solar System's Best Bet for Life?


The puzzling, fascinating surface of Jupiter's icy moon Europa looms large in this newly-reprocessed color view, made from images taken by NASA's Galileo spacecraft in the late 1990s. This is the color view of Europa from Galileo that shows the largest portion of the moon's surface at the highest resolution.

Scientists have produced this new version of what is perhaps NASA's best view Europa. The mosaic of color images was obtained in the late 1990s by NASA's Galileo spacecraft. This is the first time that NASA is publishing a version of the scene produced using modern image processing techniques.

An earlier, lower-resolution version of the view, published in 2001, featured colors that had been strongly enhanced. The new image more closely approximates what the human eye would see. Space imaging enthusiasts have produced their own versions of the view using the publicly available data, but NASA has not previously issued its own rendition using near-natural color.

The image features many long, curving and linear fractures in the moon's bright ice shell. Scientists are eager to learn if the reddish-brown fractures, and other markings spattered across the surface, contain clues about the geological history of Europa and the chemistry of the global ocean that is thought to exist beneath the ice.

The view was previously released as a mosaic with lower resolution and strongly enhanced color. To create this new version, the images were assembled into a realistic color view of the surface that approximates how Europa would appear to the human eye. The scene shows the stunning diversity of Europa's surface geology. Long, linear cracks and ridges crisscross the surface, interrupted by regions of disrupted terrain where the surface ice crust has been broken up and re-frozen into new patterns.

Color variations across the surface are associated with differences in geologic feature type and location. For example, areas that appear blue or white contain relatively pure water ice, while reddish and brownish areas include non-ice components in higher concentrations. The polar regions, visible at the left and right of this view, are noticeably bluer than the more equatorial latitudes, which look more white. This color variation is thought to be due to differences in ice grain size in the two locations.

Hidden beneath Europa's icy surface is perhaps the most promising place in our solar system beyond Earth to look for present-day environments that are suitable for life. The Galileo mission found strong evidence that a subsurface ocean of salty water is in contact with a rocky seafloor. The cycling of material between the ocean and ice shell could potentially provide sources of chemical energy that could sustain simple life forms.

Over the centuries, Europa, has provided an abundance of mysteries. These culminated in what may have been a literal explosion in December 2012, when a cloud of water vapor was seen 20 miles over its south pole. This eruption was tiny on the cosmic scale, but enormous in its importance to astrobiology.

Outside of Earth, Europa may be the most hospitable home for life inside the Solar System. Four billion years of tidal heating and a liquid ocean may have given rise to something we can identify as life. A man-made satellite in the Jovian system could potentially capture traces of that life in the water vapor shooting from Europa’s surface. Yet, in spite of the exciting science, a dedicated mission to Jupiter hasn’t launched in a generation.

Though Europa was discovered more than 400 years ago, it wasn’t until deep space satellites came along that we had our first good look at one of the most luminous objects in the Solar System. Between 1973 and 1993, eight satellites flew past Europa. Each dispelled some of the uncertainties surrounding this mysterious body orbiting 390.4 million miles (628.3 million kilometers) away.

The first arrived in 1973. The Pioneer 10 satellite sent back the first close-up photograph of that bright moon. Europa reflects back into space 64 percent of the light that falls on its surface. By contrast, Earth’s light reflectivity, or albedo, is 33 percent. Venus’ is 76 percent. In other words, Europa’s brightness falls somewhere between Earth’s liquid oceans and Venus’ constant cloud cover.

But what creates the brightness? With the Sun 2,000 times further away, Europa probably isn’t covered in liquid water the way that the Earth is. As for clouds, Europa is slightly smaller than our Moon. It lacks the gravity to maintain a substantial atmosphere. A planet coated in solid ice would explain Pioneer’s observations, but it doesn't account for one big effect: Jupiter’s tidal force. Europa’s proximity to Jupiter means that it might very well be heated from the inside out, melting some of the ice at least near the center.

Shortly before the arrival of the next satellite into the Jovian system, another suggestion was made: Europa might have three layers. In this model, the innermost core would be silica. The outermost core would be ice. The pressure of being slung around Jupiter every 3.5 days might generate enough tidal heating to maintain a liquid ocean in between. If this model were true, even though the third layer is solid, Jupiter’s tidal forces might be strong enough to crack the ice shell covering of Europa as it moves rapidly around the gas giant.

Thanks to Pioneer, Voyager and Galileo, we had learned more in three decades than in the preceding five centuries. The brightness of the ice was known to be the result of continual surface renewal. The enormous cracks, sometimes referred to as “flexi”, appear to originate when the solid ice shell flexes as Jupiter pulls on Europa.

In a nod towards the three-layer-model, Galileo’s measurements also indicated that a large, salt water ocean might well exist beneath the ice shell. While all this was being discovered half a billion miles away, things were being uncovered in our own backyard that made the possibility of Europa’s oceans even more exciting.

In 1977, hydrothermal vents teeming with life were discovered deep within Earth’s oceans. This was the first proof that life could thrive in the absence of light, using heat as a source of chemical power. This led to the current understanding that life can prosper as long as there is heat and water. With a probable ocean and definite heat source, Europa suddenly became a leading candidate in the search for habitability.

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Friday, 21 November 2014

Image of the Day: Bizarre Red Supergaint and Neutron Star Hybrid --"A 'Theoretical' Object Proposed in 1974"

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Betelgeuse is one of the most massive known stars, almost the size of the orbit of Jupiter, surrounded by a nebula, which is much bigger than the supergiant itself, stretching 60 billion kilometres away from the star's surface — about 400 times the distance of the Earth from the Sun. Red supergiants like Betelgeuse represent one of the last stages in the life of a massive star in which the star increases in size, and expels material into space at a tremendous rate — it sheds immense quantities of material equal to the mass of the Sun in just 10 000 years.

In a discovery decades in the making, scientists have detected the first of a “theoretical” class of stars first proposed in 1975 by physicist Kip Thorne and astronomer Anna Żytkow. Thorne-Żytkow objects (TŻOs) are hybrids of red supergiant and neutron stars that superficially resemble normal red supergiants, such as Betelgeuse. They differ, however, in their distinct chemical signatures that result from unique activity in their stellar interiors.

The astronomers made their discovery with the 6.5-meter Magellan Clay telescope on Las Campanas, in Chile. They examined the spectrum of light emitted from apparent red supergiants, which tells them what elements are present. When the spectrum of one particular star—HV 2112 in the Small Magellanic Cloud―was first displayed, the observers were quite surprised by some of the unusual features. Morrell explained, “I don’t know what this is, but I know that I like it!”T

TŻOs are thought to be formed by the interaction of two massive stars―a red supergiant and a neutron star formed during a supernova explosion―in a close binary system. While the exact mechanism is uncertain, the most commonly held theory suggests that, during the evolutionary interaction of the two stars, the much more massive red supergiant essentially swallows the neutron star, which spirals into the core of the red supergiant.

While normal red supergiants derive their energy from nuclear fusion in their cores, TŻOs are powered by the unusual activity of the absorbed neutron stars in their cores. The discovery of this TŻO thus provides evidence of a model of stellar interiors previously undetected by astronomers.

When Emily Levesque of the University of Colorado Boulder, and her colleagues took a close look at the subtle lines in the spectrum they found that it contained excess rubidium, lithium and molybdenum. Past research has shown that normal stellar processes can create each of these elements. But high abundances of all three of these at the temperatures typical of red supergiants is a unique signature of TŻOs.

“Studying these objects is exciting because it represents a completely new model of how stellar interiors can work," Levesque said. "In these interiors we also have a new way of producing heavy elements in our universe. You've heard that everything is made of ‘star stuff’—inside these stars we might now have a new way to make some of it.”

The study, accepted for publication in the Monthly Notices of the Royal Astronomical Society Letters, was co-authored by Philip Massey, of Lowell Observatory in Flagstaff, Arizona; Anna Żytkow of the University of Cambridge in the U.K.; and Nidia Morrell of the Carnegie Observatories in La Serena, Chile.

“I am extremely happy that observational confirmation of our theoretical prediction has started to emerge,” Żytkow said. “Since Kip Thorne and I proposed our models of stars with neutron cores, people were not able to disprove our work. If theory is sound, experimental confirmation shows up sooner or later. So it was a matter of identification of a promising group of stars, getting telescope time and proceeding with the project.”

The team is careful to point out that HV 2112 displays some chemical characteristics that don’t quite match theoretical models. Massey points out, “We could, of course, be wrong. There are some minor inconsistencies between some of the details of what we found and what theory predicts. But the theoretical predictions are quite old, and there have been a lot of improvements in the theory since then. Hopefully our discovery will spur additional work on the theoretical side now.”

This work was partially supported by NASA and the National Science Foundation.

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Thursday, 20 November 2014

"Large Chunk of Milky Way's 1st Generation Stars are Missing"


Thanks to the NASA/ESA Hubble Space Telescope, some of the most mysterious cosmic residents have just become even more puzzling. New observations of globular clusters in a small galaxy show they are very similar to those found in the Milky Way, and so must have formed in a similar way. One of the leading theories on how these clusters form predicts that globular clusters should only be found nestled in among large quantities of old stars. But these old stars, though rife in the Milky Way, are not present in this small galaxy, and so, the mystery deepens.

Globular clusters -- large balls of stars that orbit the centres of galaxies, but can lie very far from them -- remain one of the biggest cosmic mysteries. They were once thought to consist of a single population of stars that all formed together. However, research has since shown that many of the Milky Way's globular clusters had far more complex formation histories and are made up of at least two distinct populations of stars.

Of these populations, around half the stars are a single generation of normal stars that were thought to form first, and the other half form a second generation of stars, which are polluted with different chemical elements. In particular, the polluted stars contain up to 50-100 times more nitrogen than the first generation of stars.

The proportion of polluted stars found in the Milky Way's globular clusters is much higher than astronomers expected, suggesting that a large chunk of the first generation star population is missing. A leading explanation for this is that the clusters once contained many more stars but a large fraction of the first generation stars were ejected from the cluster at some time in its past.

This explanation makes sense for globular clusters in the Milky Way, where the ejected stars could easily hide among the many similar, old stars in the vast halo, but the new observations, which look at this type of cluster in a much smaller galaxy, call this theory into question.

Astronomers used Hubble's Wide Field Camera 3 (WFC3) to observe four globular clusters in a small nearby galaxy known as the Fornax Dwarf Spheroidal galaxy (image above).

"We knew that the Milky Way's clusters were more complex than was originally thought, and there are theories to explain why. But to really test our theories about how these clusters form we needed to know what happened in other environments," says Søren Larsen of Radboud University in Nijmegen, the Netherlands, lead author of the new paper. "Before now we didn't know whether globular clusters in smaller galaxies had multiple generations or not, but our observations show clearly that they do!"

The astronomers' detailed observations of the four Fornax clusters show that they also contain a second polluted population of stars and indicate that not only did they form in a similar way to one another, their formation process is also similar to clusters in the Milky Way. Specifically, the astronomers used the Hubble observations to measure the amount of nitrogen in the cluster stars, and found that about half of the stars in each cluster are polluted at the same level that is seen in Milky Way's globular clusters.

This high proportion of polluted second generation stars means that the Fornax globular clusters' formation should be covered by the same theory as those in the Milky Way.

Based on the number of polluted stars in these clusters they would have to have been up to ten times more massive in the past, before kicking out huge numbers of their first generation stars and reducing to their current size. But, unlike the Milky Way, the galaxy that hosts these clusters doesn't have enough old stars to account for the huge number that were supposedly banished from the clusters.

"If these kicked-out stars were there, we would see them -- but we don't!" explains Frank Grundahl of Aarhus University in Denmark, co-author on the paper. "Our leading formation theory just can't be right. There's nowhere that Fornax could have hidden these ejected stars, so it appears that the clusters couldn't have been so much larger in the past."

This finding means that a leading theory on how these mixed generation globular clusters formed cannot be correct and astronomers will have to think once more about how these mysterious objects, in the Milky Way and further afield, came to exist.

The new work is detailed in a paper published today, 20 November 2014, in The Astrophysical Journal.

The Daily Galaxt via ESA/Hubble Information Centre

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Wednesday, 19 November 2014

Spooky Discovery About the Largest Structure in the Universe --"Vast Quasar Groupings Found in Astounding Alignment"


On January 11, 2013, the discovery of a vast grouping of 73s quasars, a form of supermassive black hole active galactic nuclei, with a minimum diameter of 1.4 billion light-years, stretched over four billion light-years at its widest point was announced by the University of Central Lancashire, as the largest known structure in the universe LQGs are thought to be precursors to the sheets, walls and filaments of galaxies found in the relatively nearby universe. The existence of structures of the magnitude of large quasar clusters was believed theoretically impossible. Cosmological structures had been believed to have a size limit of approximately 1.2 billion light-years.

Quasars are the nuclei of galaxies from the early days of the universe that undergo brief periods of extremely high brightness that make them visible across huge distances. These periods are 'brief' in astrophysics terms but actually last 10-100 million years. Since 1982 it has been known that quasars tend to group together in clumps or 'structures' of surprisingly large sizes, forming large quasar groups. The whole of Earth’s history is equal to the time that it takes photons to travel across the vast expanse of the LQG. As the largest known structure in the universe, the LQG is so vast that it would take a spaceship traveling at the speed of light some 4 billion years to cross it.

The LQG also challenges the Cosmological Principle, the assumption that the universe, when viewed at a sufficiently large scale, looks the same no matter where you are observing it from. The modern theory of cosmology is based on the work of Albert Einstein, and depends on the assumption of the Cosmological Principle. The Principle is assumed but has never been demonstrated observationally 'beyond reasonable doubt'.

This year, a team led by Damien Hutsemékers from the University of Liège in Belgium used the FORS instrument on the VLT to study 93 quasars that were known to form huge groupings spread over billions of light-years, seen at a time when the Universe was about one third of its current age. "The first odd thing we noticed was that some of the quasars' rotation axis were aligned with each other -- despite the fact that these quasars are separated by billions of light-years," said Hutsemékers.

"The alignments in the new data, on scales even bigger than current predictions from simulations, may be a hint that there is a missing ingredient in our current models of the cosmos," observed Dominique Sluse of the Argelander-Institut für Astronomie in Bonn, Germany and University of Liège.

The team then went further and looked to see if the rotation axes were linked, not just to each other, but also to the structure of the Universe on large scales at that time.

When astronomers look at the distribution of galaxies on scales of billions of light-years they find that they are not evenly distributed. They form a cosmic web of filaments and clumps around huge voids where galaxies are scarce. This intriguing and beautiful arrangement of material is known as large-scale structure.

The new VLT results indicate that the rotation axes of the quasars tend to be parallel to the large-scale structures in which they find themselves. So, if the quasars are in a long filament then the spins of the central black holes will point along the filament. The researchers estimate that the probability that these alignments are simply the result of chance is less than 1%.

"A correlation between the orientation of quasars and the structurethey belong to is an important prediction of numerical models of evolution of our Universe. Our data provide the first observational confirmation of this effect, on scales much larger that what had been observed to date for normal galaxies," adds Sluse.

The team could not see the rotation axes or the jets of the quasars directly. Instead they measured the polarisation of the light from each quasar and, for 19 of them, found a significantly polarised signal. The direction of this polarisation, combined with other information, could be used to deduce the angle of the accretion disc and hence the direction of the spin axis of the quasar.

Whole clusters of galaxies can be 2-3 Mpc across but LQGs can be 200 Mpc or more across. Based on the Cosmological Principle and the modern theory of cosmology, calculations suggest that astrophysicists should not be able to find a structure larger than 370 Mpc. The newly discovered LQG however has a typical dimension of 500 Mpc. But because it is elongated, its longest dimension is 1200 Mpc (or 4 billion light years) - some 1600 times larger than the distance from the Milky Way to Andromeda.

"While it is difficult to fathom the scale of this LQG, we can say quite definitely it is the largest structure ever seen in the entire universe," says Dr Clowes of University of Central Lancashire'sJeremiah Horrocks Institute. "This is hugely exciting – not least because it runs counter to our current understanding of the scale of the universe. Even traveling at the speed of light, it would take 4 billion years to cross. This is significant not just because of its size but also because it challenges the Cosmological Principle, which has been widely accepted since Einstein. Our team has been looking at similar cases which add further weight to this challenge and we will be continuing to investigate these fascinating phenomena."

The team published their results in the journal Monthly Notices of the Royal Astronomical Society.

This research was presented in a paper entitled "Alignment of quasar polarizations with large-scale structures", by D. Hutsemékers et al., to appear in the journal Astronomy & Astrophysics on 19 November 2014.

The ESO team is composed of D. Hutsemékers (Institut d'Astrophysique et de Géophysique, Université de Liège, Liège, Belgium), L. Braibant (Liège), V. Pelgrims (Liège) and D. Sluse (Argelander-Institut für Astronomie, Bonn, Germany; Liège).

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Mystery of Missing Quasars at Galaxy Centers --"May Provide 1st Real Signal of Dark Matter"


"It is possible that pulsars imploding into black holes may provide the first concrete signal of particulate dark matter," said study co-author Joseph Bramante, a physicist at the University of Notre Dame. “In 2013, the first pulsar at the galactic center was detected, and this observation has deepened the mystery of these stellar objects,” explained Bramante. “Prior to this detection, it was thought that pulsars at the galactic center might simply be shielded from observation by dense material in the center of the galaxy.”

In a new paper, co-authored by University of Notre Dame astrophysicist Joseph Bramante and his colleague at the University of Chicago, Tim Linden, discusses how detecting imploding pulsars may lead to insights about the properties of dark matter and how dark matter could explain the absence of pulsars in the galactic center. Dark matter, which makes up approximately 25 percent of the matter in the universe, is a very dense type of matter that does not emit a significant amount of light. A particular kind of dark matter could destroy pulsars at the galactic center by falling into the pulsars and forming black holes that swallow them.

“Observations of pulsars imploding into black holes could provide important clues to the properties of dark matter, specifically indicating it is asymmetric, just like visible matter,” said Bramante.

Pulsars, or pulsating stars, are rotating neutron stars that emit pulses of light visible to astronomers on Earth. Pulsars are created from the collapsing cores of supermassive stars that have exploded into supernovae. These supermassive stars, 10 to 40 times the mass of the sun, have been found at the center of the galaxy, leading astronomers to predict a certain number of pulsars should also reside there, but that predicted number of pulsars has not yet been observed.

The paper also explains how the researchers showed that the presently unknown mass and quantum couplings of dark matter could be found by determining the age at which a pulsar is swallowed by a dark matter black hole. One predictor of this pulsar-collapsing dark matter is a maximum age for pulsars, which gets higher the further away from the galactic center the pulsars are because there is less dark matter away from the center.

The next steps in this work for Bramante and his collaborators includes building and testing a model of dark matter to ensure the model meets all other cosmological and astrophysical dark matter observations.

The image at the top of the page shows galaxy, called Henize 2-10, a blob-shaped dwarf galaxy 30 million light-years away. The tiny galaxy has a colossal black hole at its center and could be a transition between young, small galaxies and massive spirals like our Milky Way, suggesting that galaxies form around central black holes, not the other way around. Astronomers suggest think that Henize 2-10 could be a nearby example of some of the first galaxies ever formed in the universe.

The paper, “Detecting Dark Matter with Imploding Pulsars in the Galactic Center,” was recently published in Physical Review Letters, the flagship journal for the American Physical Society.

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Tuesday, 18 November 2014

"Gravity May Answer Last Great Unknown in Standard Model of Physics"


New research investigates the last unknown parameter in the Standard Model – the interaction between the Higgs particle and gravity. “The Standard Model of particle physics, which scientists use to explain elementary particles and their interactions, has so far not provided an answer to why the universe did not collapse following the Big Bang,” explains Professor Arttu Rajantie, from the Department of Physics at Imperial College London.

“Our aim is to measure the interaction between gravity and the Higgs field using cosmological data,” says Professor Rajantie. “If we are able to do that, we will have supplied the last unknown number in the Standard Model of particle physics and be closer to answering fundamental questions about how we are all here.”

Studies of the Higgs particle – discovered at CERN in 2012 and responsible for giving mass to all particles – have suggested that the production of Higgs particles during the accelerating expansion of the very early universe (inflation) should have led to instability and collapse.

Scientists have been trying to find out why this didn’t happen, leading to theories that there must be some new physics that will help explain the origins of the universe that has not yet been discovered. Physicists from Imperial College London, and the Universities of Copenhagen and Helsinki, however, believe there is a simpler explanation.

In a new study in Physical Review Letters, the team describe how the spacetime curvature – in effect, gravity – provided the stability needed for the universe to survive expansion in that early period. The team investigated the interaction between the Higgs particles and gravity, taking into account how it would vary with energy. They show that even a small interaction would have been enough to stabilise the universe against decay.

“Our research investigates the last unknown parameter in the Standard Model – the interaction between the Higgs particle and gravity. This parameter cannot be measured in particle accelerator experiments, but it has a big effect on the Higgs instability during inflation. Even a relatively small value is enough to explain the survival of the universe without any new physics!”

The team plan to continue their research using cosmological observations to look at this interaction in more detail and explain what effect it would have had on the development of the early universe. In particular, they will use data from current and future European Space Agency missions measuring cosmic microwave background radiation and gravitational waves.

The research is funded by the Science and Technology Facilities Council, along with the Villum Foundation, in Denmark, and the Academy of Finland.

The image at the top of the page shows Globular cluster Messier 15, located some 35,000 light-years away in the constellation of Pegasus (The Winged Horse). It is one of the oldest clusters known, with an age of around 12 billion years. Both very hot blue stars and cooler golden stars can be seen swarming together in the image, becoming more concentrated towards the cluster's bright center. Messier 15 is one of the densest globular clusters known, with most of its mass concentrated at its core. As well as stars, Messier 15 was the first cluster known to host a planetary nebula, and it has been found to have a rare type of black hole at its centre. This image is made up of observations from Hubble's Wide Field Camera 3 and Advanced Camera for Surveys in the ultraviolet, infrared, and optical parts of the spectrum. (NASA, ESA

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China Preps for 2020 Mars' Landing


Chinese scientists are planning to launch a Mars rover "around 2020", state media reported on Tuesday, as the country pours billions into its space programme and works to catch up with the US and Europe. Although the government has not officially announced plans for a Mars mission, officials from the China National Space Administration are currently lobbying to have it put on the agenda and have begun "preliminary research", the state-run China Daily reported.

"We plan to conduct the Mars mission around 2020, which will include the probe's orbiting, landing and roaming," Peng Tao, a space expert with the China Academy of Space Technology, was quoted by China Daily as saying. "By contrast, other nations will need multiple missions to achieve those three steps."

The statements came less than a week after prototypes for the Mars rover were debuted at the China International Aviation and Aerospace Exhibition. China's recent space efforts have been focused on exploring the moon. The nation's first lunar rover -- the Yutu, or Jade Rabbit -- was launched late last year, but it has since been beset by mechanical troubles.

The planned Mars rover will be bigger than the Yutu in order to deal with the harsher terrain, China Daily quoted space officials as saying. Scientists are now focused on sending a manned mission to the moon and returning samples safely back to Earth.

The US has landed two rovers on Mars and India successfully put a satellite into orbit around the red planet in September. The former Soviet Union and the European Space Agency have also sent missions to Mars. China's first attempt to send a satellite into Mars orbit foundered in 2011 when the Russian rocket carrying the payload failed to make it out of the Earth's orbit.

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Monday, 17 November 2014

Ancient Antarctica Lake Provides Clues to One of the Unsolved Mysteries of Early Earth

The Antarctic discovery in an ancient lake in April of 2011 helped scientists better understand the conditions under which the Earth's primitive life-forms thrived. “It’s like going back to early Earth,” said Dawn Sumner, a geobiologist at the University of California, Davis, describing her explorations of the eerie depths of East Antarctica’s Lake Untersee where Sumner and her colleagues, led by Dale Andersen of the SETI Institute in Mountain View, Calif., discovered otherworldly mounds of Photosynthetic microbial stromatolites.


"The weather looks to be pretty good tomorrow, with clear skies and low winds, at least for Novo. Monday and Tuesday the weather may go down with 45 kt winds so we need to get the camp up as soon as least a few tents anyway. It will be great to get back to the lake, and everyone is pretty excited now." Reports Dale Andersen of the SETI Institute in Mountain View, Calif in his Field Report from Lake Untersee, Antarctica 15 November 2014.

The stromatolites, built layer by layer by bacteria on the lake bottom, resemble similar structures that first appeared billions of years ago and remain in fossil form as one of the oldest widespread records of ancient life dating from 3 billion years ago or more, to understand how life got a foothold on Earth.


Lake Untersee is located at 71°20'S, 13°45'E in the Otto-von-Gruber-Gebirge (Gruber Mountains) of central Dronning Maud Land. [Download Google Earth .kmz file of Lake Untersee]. The lake is 563 meters above sea level, with an area of 11.4 square kilometers and is the largest surface lake in East Antarctica.

The purple-bluish mounds are composed of long, stringy cyanobacteria, ancient photosynthetic organisms. Similar to coral reef organisms, the bacteria takes decades to build each layer in Untersee’s icy waters, Sumner said, so the mounds may have taken thousands of years to accumulate.

Today, stromatolites are found in only a few spots in the ocean, including off the western coast of Australia and in the Bahamas. They they have also been found thriving in freshwater environments, such as super-salty lakes high in the Andes and in a few of Antarctica’s other freshwater lakes.

But scientists were stunned by the size and shape of the purplish stromatolite mounds built by Phormidium bacteria in Untersee's extremely alkaline waters and high concentrations of dissolved methane, are unique reaching up to half a meter high, dotting the lake floor. “It totally blew us away,” Andersen said. “We had never seen anything like that.” The stromatolite mounds were found adjacent to smaller, pinnacle-shaped lumps made of another bacterial group, Leptolyngbya.

“Everywhere else that we’ve looked you have a gradation between the structures,” like in bacterial mats sprawling around Yellowstone’s hot springs, she said. “There’s something very special about this particular example that’s allowing these large conical stromatolites to form.”

The widespread disappearance of stromatolites, the earliest visible manifestation of life on Earth, may have been driven by single-celled organisms called foraminifera. Stromatolites (“layered rocks”) are structures made of calcium carbonate and shaped by the actions of photosynthetic cyanobacteria and other microbes that trapped and bound grains of coastal sediment into fine layers. They showed up in great abundance along shorelines all over the world about 3.5 billion years ago.

“Stromatolites were one of the earliest examples of the intimate connection between biology—living things—and geology—the structure of the Earth itself,” said Woods Hole Oceanographic Institution (WHOI) geobiologist Joan Bernhard.

The growing bacterial community secreted sticky compounds that bound the sediment grains around themselves, creating a mineral “microfabric” that accumulated to become massive formations. Stromatolites dominated the scene for more than two billion years, until late in the Proterozoic Eon.

“Then, around 1 billion years ago, their diversity and their fossil abundance begin to take a nosedive,” said Bernhard. All over the globe, over a period of millions of years, the layered formations that had been so abundant and diverse began to disappear. To paleontologists, their loss was almost as dramatic as the extinction of the dinosaurs millions of years later, although not as complete: Living stromatolites can still be found today, in limited and widely scattered locales, as if a few velociraptors still roamed in remote valleys.

Just as puzzling is the sudden appearance in the fossil record of different formations called thrombolites (“clotted stones”). Like stromatolites, thrombolites are produced through the action of microbes on sediment and minerals. Unlike stromatolites, they are clumpy, rather than finely layered.

It’s not known whether stromatolites became thrombolites, or whether thrombolites arose independently of the decline in strombolites. Hypotheses proposed to explain both include changes in ocean chemistry and the appearance of multicellular life forms that might have preyed on the microbes responsible for their structure.

Bernhard and Edgcomb thought foraminifera might have played a role. Foraminifera (or “forams,” for short) are protists, the kingdom that includes amoeba, ciliates, and other groups formerly referred to as “protozoa.” They are abundant in modern-day oceanic sediments, where they use numerous slender projections called pseudopods to engulf prey, to move, and to continually explore their immediate environment. Despite their known ability to disturb modern sediments, their possible role in the loss of stromatolites and appearance of thrombolites had never been considered.

The Woods Hole researchers examined modern stromatolites and thrombolites from Highborne Cay in the Bahamas for the presence of foraminifera. Using microscopic and rRNA sequencing techniques, they found forams in both kinds of structures. Thrombolites were home to a greater diversity of foraminifera and were especially rich in forams that secrete an organic sheath around themselves. These “thecate” foraminifera were probably the first kinds of forams to evolve, not long (in geologic terms) before stromatolites began to decline.

“The timing of their appearance corresponds with the decline of layered stromatolites and the appearance of thrombolites in the fossil record,” said Edgcomb. “That lends support to the idea that it could have been forams that drove their evolution.”

Next, Bernhard, Edgcomb, and postdoctoral investigator Anna McIntyre-Wressnig created an experimental scenario that mimicked what might have happened a billion years ago.

“No one will ever be able to re-create the Proterozoic exactly, because life has evolved since then, but you do the best you can,” Edgcomb said.

They started with chunks of modern-day stromatolites collected at Highborne Cay, and seeded them with foraminifera found in modern-day thrombolites. Then they waited to see what effect, if any, the added forams had on the stromatolites. After about six months, the finely layered arrangement characteristic of stromatolites had changed to a jumbled arrangement more like that of thrombolites. Even their fine structure, as revealed by CAT scans, resembled that of thrombolites collected from the wild. “The forams obliterated the microfabric,” said Bernhard.

That result was intriguing, but it did not prove that the changes in the structure were due to the activities of the foraminifera. Just being brought into the lab might have caused the changes. But the researchers included a control in their experiment: They seeded foraminifera onto freshly-collected stromatolites as before, but also treated them with colchicine, a drug that prevented them from sending out pseudopods. “They’re held hostage,” said Bernhard. “They’re in there, but they can’t eat, they can’t move.”

After about six months, the foraminifera were still present and alive—but the rock’s structure had not become more clotted like a thrombolite. It was still layered. The researchers concluded that active foraminifera can reshape the fabric of stromatolites and could have instigated the loss of those formations and the appearance of thrombolites.

The findings, by scientists at Woods Hole Oceanographic Institution (WHOI); Massachusetts Institute of Technology; the University of Connecticut; Harvard Medical School; and Beth Israel Deaconess Medical Center, Boston, were published online in the Proceedings of the National Academy of Sciences.

The Woods Hole Oceanographic Institution is a private, non-profit organization on Cape Cod, Mass., dedicated to marine research, engineering, and higher education. Established in 1930 on a recommendation from the National Academy of Sciences, its primary mission is to understand the oceans and their interaction with the Earth as a whole, and to communicate a basic understanding of the oceans’ role in the changing global environment.

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Saturday, 15 November 2014

Dying Philae Robot Lab Streamed Back Data on an Alien World -- "May Shed Light on Origins of Life"

Protoplanetary_disk (1)

Lacking power, its instruments and most systems went into standby mode after three days of non-stop work, the Rosetta mission sent back data that will keep scientists busy for years. "The data collected by Philae and Rosetta is set to make this mission a game-changer in cometary science," said Matt Taylor, Rosetta project scientist. Europe's science probe streamed data from its experiments back to its mother ship Rosetta in the final hours before its battery ran down. This included the outcome of an eagerly-waited chemistry test of a sample drilled from the comet's icy and dusty surface, scientists said.

Conceived more than 20 years ago, the Rosetta mission aims at shedding light on the origins of the Solar System 4.6 billion years ago, and maybe even life on Earth. A theory gaining ground in astrophysics is that the fledgling Earth was pounded by these bodies of cosmic ice and carbon-rich dust, seeding our planet with the basics to start life.

Philae is the island in the river Nile on which an obelisk was found that had a bilingual inscription including the names of Cleopatra and Ptolemy in Egyptian hieroglyphs. This provided the French historian Jean-François Champollion with the final clues that enabled him to decipher the hieroglyphs of the Rosetta Stone and unlock the secrets of the civilisation of ancient Egypt. Just as the Philae Obelisk and the Rosetta Stone provided the keys to an ancient civilisation, the Philae lander and the Rosetta orbiter aim to unlock the mysteries of the oldest building blocks of our Solar System - comets.


The data streamed back from Comet Churyumov-Gerasimenko allow scientists to look back 4600 million years to an epoch when no planets existed and only a vast swarm of asteroids and comets surrounded the Sun. The Philae data will determine the physical properties of the comet's surface and subsurface and their chemical, mineralogical and isotopic composition. This will complement the orbiter's studies of the overall characterisation of the comet's dynamic properties and surface morphology. Philae may provide the final clues enabling the Rosetta mission to unlock the secrets of how life began on Earth.

Philae had landed in a dark shadow after a bouncy triple touchdown Wednesday. It did not get enough sunlight to recharge its batteries sufficiently to extend its mission beyond its initial 60-hour work program. Mission engineers do not rule out making contact with the lander in the coming months as Comet 67P/Churyumov-Gerasimenko moves closer to the Sun.

Rosetta and its payload travelled more than six billion kilometres (3.75 billion miles), racing around the inner Solar System before they caught up with the comet in August this year. On Wednesday, Philae bade farewell to its mother ship and descended to a comet traveling at 18 kilometres (11 miles) per second, 510 million kilometres (320 million miles) from Earth.

The touchdown did not go entirely as planned -- hardly a surprise in an operation some gloomily predicted had only a one-in-two chance of success. Philae landed smack in the middle of its targeted site, but a pair of anchoring harpoons failed to deploy. It rebounded, touched down again, bounced up once more and then landed for the third time at a place believed to be about a kilometre (half a mile) from the landing site.

Philae found itself in the shadow of a cliff, tilted at an angle that left one of its three legs pointed to the sky.

Weighing 100 kilos (220 pounds) on Earth, Philae has a mass of just one gramme (0.03 of an ounce) -- less than a feather -- on the low-gravity, four-kilometre comet. That meant just a jolt could have caused it to drift off into space. And lack of sunlight for its solar panels meant it had to survive on a battery with a charge of around 60 hours, enough to carry out its scheduled scientific work.

Stacked against the odds, the scientists resorted to every trick possible to use power miserly and keep Rosetta working without causing it to drift away. Using the lander's toolkit of 10 instruments, they started with passive observation -- taking pictures, measuring the comet's density, temperature, and internal structure, "sniffing" molecules of gas from its surface -- that would not move the craft.

Finally, in the most important but riskiest experiment of all, they drilled a core of material out of the comet surface to analyse its chemical signature.All the data had to be stored and dispatched back to Rosetta as the power indicators shrank towards the red zone.

"We received everything," mission scientist Jean-Pierre Bibring told AFP. "The word is 'fabulous,' just 'fabulous.'

The "67P" comet is due to loop around the Sun next year, flaring gas from its head and leaving a spectacular icy trail of ice from water stripped from its surface.Rosetta will escort it until the comet heads back out towards the depths of the Solar System in December 2015.

Image at top of page shows the protoplanetary disk of gas and dust that led to the formation of the Sun and our solar system's planets. NASA

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Friday, 14 November 2014

"Race Against Time" --Philae Comet Probe's Battery Fading Fast


Robot lab Philae drilled into its host comet Friday with just hours of battery left, but may lose power before it can transmit results of a much-anticipated attempt to probe below the surface, mission scientists said. Charged with 60 hours of onboard power, the lander bounced twice after initial touchdown Wednesday, settling at an angle in a crevice in an unknown location, shadowed from sunlight that could potentially have extended its battery life. Besides 60 hours of power on its main battery, Philae was also designed with solar panels to recharge and extend the mission duration by as much as possible. But in the lander's dark location, evident from photos and data it sent home, one solar panel was only receiving about 80 minutes of sunlight per 12.4-hour comet day and two others 20 or 30 minutes -- much less than the six or seven hours engineers had bargained on.

With its energy supply fast winding down lander manager Stephan Ulamec said the drill was "started" on Friday, but contact between Philae and its orbiting mothership Rosetta was lost soon thereafter. There are two communications windows per day -- the next is due to open 2100 GMT -- by when Philae may have entered hibernation.

"Maybe the battery will be empty before we get contact again" to upload the data, which Philae transmits to Earth via Rosetta, said Ulamec, who urged onlookers to "cross your fingers". "If we don't receive any data it's probably because the battery is flat."

It was not certain the drill had actually pierced the surface of comet 67P/Churyumov-Gerasimenko, which is racing towards the Sun at 18 kilometres (11 miles) per second.

Samples from its drill, one of 10 onboard experiments, had been among the most highly anticipated results from Philae's mission, with scientists hoping for clues to the formation of the Solar System and even the appearance of life on Earth.

But mission controllers underlined the exploration has already been a massive success, saying Philae's rough start has not stopped it from experimenting more or less as planned and relaying valuable data to Earth.

Washing machine-sized Philae landed on the comet after a nail-biting seven-hour, 20-km descent from its orbiting mothership Rosetta, which had travelled more than a decade and 6.5 billion kilometres (four billion miles) to get there.

The touchdown on the low-gravity comet did not go entirely according to plan, when Philae's duo of anchoring harpoons failed to deploy and it lifted off again... twice.

Ground controllers had by Friday not yet pinpointed Philae's position on the comet currently 510 million kilometres (320 million miles) from Earth.

When it eventually does fall into slumber, there is always the off chance that Philae may be jolted back to life months in the future as comet "67P" draws closer to the Sun, they added, and may then pass on outstanding data.

But, "we would have to be extremely lucky," said mission scientist Valentina Lommatsch.

So far, the 100-kilogramme (22-pound) lab has sent back the first-ever photos taken from a comet surface, and has probed the ancient Solar System traveller's surface density, temperature and composition.

Even without drilling, "we should harvest at least 70 to 80 percent of the scientific data we had expected from Philae's first (60-hour) phase," astrophysicist Philippe Gaudon, who heads the Rosetta mission at French space agency CNES, told AFP.

The 1.3-billion-euro ($1.6-billion) mission aims to unlock the secrets that comets, primordial clusters of ice and dust, are thought to hold about how the Solar System was formed around 4.6 billion years ago.

Some scientists theorise that they may even have "seeded" Earth with some of the ingredients for life.

Rosetta, with Philae riding piggyback, was hoisted into space in 2004, and reached its target in August this year, having used the gravitational pull of Earth and Mars as slingshots to build up speed.

Whatever happens to Philae, Rosetta will continue to escort the comet as it loops around the Sun. On August 13, 2015, they will come within 186 million kilometres of our star.

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