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Are Other Solvents Outside Of Water Possible For Alien Life

October 18, 2017 by  
Filed under Around The Net

Life on early Earth seems to have begun with a paradox: while life needs water as a solvent, the essential chemical backbones of early life-forming molecules fall apart in water. Our universal solvent, it turns out, can be extremely corrosive.

Some have pointed to this paradox as a sign that life, or the precursor of life, originated elsewhere and was delivered here via comets or meteorites. Others have looked for solvents that could have the necessary qualities of water without that bond-breaking corrosiveness.

In recent years the solvent often put forward as the eligible alternative to water is formamide, a clear and moderately irritating liquid consisting of hydrogen, carbon, nitrogen and oxygen. Unlike water, it does not break down the long-chain molecules needed to form the nucleic acids and proteins that make up life’s key initial instruction manual, RNA. Meanwhile it also converts via other useful reactions into key compounds needed to make nucleic acids in the first place.

Although formamide is common in star-forming regions of space, scientists have struggled to find pathways for it to be prevalent, or even locally concentrated, on early Earth. In fact, it is hardly present on Earth today except as a synthetic chemical for companies.

New research presented by Zachary Adam, an earth scientist at Harvard University, and Masashi Aono, a complex systems scientist at Earth-Life Science Institute (ELSI) at Tokyo Institute of Technology, has produced formamide by way of a surprising and reproducible pathway: bombardment with radioactive particles. 

The two and their colleagues exposed water and a mixture of two chemicals known to have existed on early Earth (hydrogen cyanide and aqueous acetonitrile) to the high-energy particles emitted from a cylinder of cobalt-60, an artificially produced radioactive isotope commonly used in cancer therapy. The result, they report, was the production of substantial amounts of formamide more quickly than earlier attempts by researchers using theoretical models and in laboratory settings. 

It remains unclear whether early Earth had enough radioactive material in the right places to produce the chemical reactions that led to the formation of formamide. And even if the conditions were right, scientists cannot yet conclude that formamide played an important role in the origin of life.

Still, the new research furthers the evidence of the possible role of alternative solvents and presents a differing picture of the basis of life. Furthermore, it is suggestive of processes that might be at work on other exoplanets as well – where solvents other than water could, with energy supplied by radioactive sources, provide the necessary setting for simple compounds to be transformed into far more complex building blocks.

“Imagine that water-based life was preceded by completely unique networks of interacting molecules that approximated, but were distinct from and followed different chemical rules, than life as we know it,” said Adam.

Their work was presented at recent gatherings of the International Society for the Study of the Origin of Life, and the Astrobiology Science Conference.

The team of Adam and Aono are hardly the first to put forward the formamide hypothesis as a solution to the water paradox, and they are also not the first to posit a role for high-energy, radioactive particles in the origin of life. 

An Italian team led by Rafaelle Saladino of Tuscia University recently proposed formamide as a chemical that would supply necessary elements for life and would avoid the “water paradox.” Since the time that Marie Curie described the phenomenon of radioactivity, scientists have proposed innumerable ways that the emission of particle-shedding atomic nuclei might have played roles, either large or small, in initiating life on Earth.

Putting formamide and radioactivty together, as Adam and Aono have done, is a potentially significant step forward, though one that needs deeper study.

“If we have formamide as a solvent, those precursor molecules can be kept stable, a kind of cradle to preserve very interesting products,” said Aono, who has moved to Tokyo-based Keio University while remaining a fellow at ELSI.

The experiment with cobalt-60 did not begin as a search for a way to concentrate the production of formamide. Rather, Adam was looking more generally into the effects of gamma rays on a variety of molecules and solvents, while Aono was exploring radioactive sources for a role in the origin of life.

The two came together somewhat serendipitously at ELSI, an origins-of-life research center created by the Japanese government. ELSI was designed to be a place for scientists from around the world and from many different disciplines to tackle some of the notoriously difficult issues in origins of life research. At ELSI, Adam, who had been unable to secure sites to conduct laboratory tests in the United States, learned from Aono about a sparingly-used (and free) cobalt-60 lab; they promptly began collaborating.

It is well known that the early Earth was bombarded by high-energy cosmic particles and gamma rays. So is the fact that numerous elements (aluminum-26, iron-60, iodine-129) have existed as radioactive isotopes that can emit radiation for minutes to millennium, and that these isotopes were more common on early Earth than today. Indeed, the three listed above are now extinct on Earth, or nearly extinct, in their natural forms.

Less known is the presence of “natural nuclear reactors” as sites where a high concentration of uranium in the presence of water has led to self-sustaining nuclear fission. Only one such spot has been found —in the Oklo region of the African nation of Gabon — where spent radioactive material was identified at 16 sites separate sites. Scientists ultimately concluded widespread natural nuclear reactions occurred in the region some 2 billion years ago.

That time frame would mean that the site would have been active well after life had begun on Earth, but it is a potential proof of concept of what could have existed elsewhere long before.

Adam and Aono remain agnostic about where the formamide-producing radioactive particles came from. But they are convinced that it is entirely possible that such reactions took place and helped produce an environment where each of the backbone precursors of RNA could readily be found in close quarters.

Current scientific thinking about how formamide appeared on Earth focuses on limited arrival via asteroid impacts or through the concentration of the chemical in evaporated water-formamide mixtures in desert-like conditions. Adam acknowledges that the prevailing scientific consensus points to low amounts of formamide on early Earth.

“We are not trying to argue to the contrary,” he said, “but we are trying to say that it may not matter.”

If you have a unique place (or places) on the Earth creating significant amounts of formamide over a long period of time through radiolysis, then an opportunity exists for the onset of some unique chemistry that can support the production of essential precursor compounds for life, Adam said.

“So, the argument then shifts to — how likely was it that this unique place existed? We only need one special location on the entire planet to meet these circumstances,” he said.

After that, the system set into motion would have the ability to bring together the chemical building blocks of life.

“That’s the possibility that we look forward to investigating in the coming years,” Adam said.

James Cleaves, an organic chemist also at ELSI and a co-author of the cobalt-60 paper, said while production of formamide from much simpler compounds represents progress, “there are no silver bullets in origin of life work. We collect facts like these, and then see where they lead.”

Courtesy-Space

Does Proxima Centauri b Have A Shiny Green Tint

October 17, 2017 by  
Filed under Around The Net

A world orbiting the sun’s closest stellar neighbor may have a shiny green tint to it — and not necessarily because it’s covered in leafy plants. 

Researchers have found a way to characterize potential auroras on the nearby exoplanet Proxima Centauri b and found that, if the planet sports oxygen in its atmosphere, the auroras may give the atmosphere a greenish cast. 

“The northern and southern lights [on Proxima Centauri b] would be at least 100 times brighter than on Earth,” Rodrigo Luger, a postdoctoral student at the University of Washington, who led the study of how the planet’s auroras could be spotted from Earth, told Space.com by email. Luger said the auroras might be so bright as to be visible with very powerful telescopes.

The active star Proxima Centauri lies only 4.2 light-years from the solar system. A small world orbits in the star’s habitable zone, the region where liquid water could survive on the surface. Its radius remains a mystery. However, scientists know it is about 1.3 times as massive as the Earth, which its initial discovers said suggests a rocky planet. 

Proxima Centauri is a small star, dimmer than Earth’s sun, so its habitable zone is closer to the star than the habitable zone of the sun. As a result, Proxima Centauri b is 20 times closer to its star than Earth is to the sun, and completes an orbit every 11.2 Earth-days. The red dwarf star is more active than Earth’s sun, firing off far more frequent flares that may douse the planet in radiation that could be harmful for potential life. 

Those same flares may help scientists better understand the planet. If Proxima Centauri b has a magnetic field, it may capture the charged particles in the flares and funnel them toward the poles, creating brilliant auroral displays. 

Observing the auroras can help researchers characterize the planet’s atmosphere. On Earth, the different color glow of the northern and southern lights corresponds to reactions with different molecules in the atmosphere. According to Luger, who presented the results at the Astrobiology Science Conference in Mesa, Arizona, in April, if Proxima Centauri b is a terrestrial world with an Earth-like atmosphere and a magnetic field, the green light of the oxygen auroras would grow 100 times stronger than on Earth.

Because of the potential for green light, the researchers dubbed such a world “the pale green dot,” a nod to Carl Sagan’s categorization of Earth as a pale blue dot.

Periods of intense stellar activity could make the auroras even brighter. While coronal mass ejections and flares have the strongest impact on generating auroras, Luger said, they aren’t really predictable in advance.

“But the sun certainly has periodic activity cycles, so if we understand those of Proxima Centauri, we might be able to use that to our advantage,” he said.

He went on to say that the extreme activity of the star may make such knowledge unnecessary — astronomers could simply count on a high likelihood that the star would flare and cause the auroras to brighten.

While several studies have described searches for auroras on gas giant exoplanets that orbit close to their parent stars, none have been spotted on worlds beyond the solar system. But Luger remains confident.

“Proxima Centauri b is optimal for auroral detection,” he said.

He gave several reasons that auroras may be soon spotted on Proxima Centauri b. The planet is nearby — it’s the closest known exoplanet to Earth — making it easier for instruments to collect detailed observations. The extreme magnetic activity of the star, coupled with the planet’s close orbit, means Proxima Centauri b is bombarded with solar particles far more vigorously than Earth. At the same time, the star is faint, so a glowing green planet would show up more easily than it would around a sun-like star. Finally, the short orbit means that the world moves around its sun at a rapid clip; when a light source is moving toward or away from an observer, this motion can be observed through a phenomenon called redshift, or Doppler shift. Luger said the Doppler shift of the auroras’ light waves would be significantly larger than they would be on their own, making lines that would otherwise be hard to see more visible. That would make it easier to identify any oxygen in the atmosphere.

Unfortunately, this “pale green dot” won’t be spotted with current telescopes. NASA’s upcoming powerhouse telescope ― the James Webb Space Telescope ― will hunt for infrared light, so Luger said it won’t be able to detect the green oxygen aurora, which is in the visible light range.

“Our best bet for detection is the [Thirty-Meter Telescope] or similar next-generation extremely large telescopes,” he said.

The Thirty-Meter Telescope (TMT) — so-named because its primary mirror would be 30 meters (98 feet) wide — began construction on Hawaii’s Mauna Kea peak before it was halted in 2015 after protests over the sacred nature of the land. The project remains at a halt today, though some astronomers have lauded the benefits of moving the telescope to Spain’s Canary Islands.

But even TMT would take some time to identify the signature of oxygen from the auroras, with Luger estimating “tens of hours” of observation. The same is true for the Large UV/Opitcal/Infrared Survey (LUVOIR), a proposed design for a telescope with a primary mirror between 9 and 15 meters (30 and 50 feet). With telescope time extremely competitive, it could be hard to study the system so extensively.

In order to produce auroras, a planet must have a magnetic field. Out of the four terrestrial planets in Earth’s solar system, only two have a worldwide field — Earth and Mercury. Mars has a patchy field, and Venus has none. If Proxima Centauri b is similarly lacking, it might not produce auroras.

However, the planet may get a brightness boost from airglow, the faint emission of light from the atmosphere that keeps nighttime on Earth from ever being completely dark.

“The planet is likely also to have strong airglow, which is planetwide,” Luger said. “Airglow is not generated by magnetic fields, and is typically weaker than aurorae, so we did not calculate it. But it should be quite strong on Proxima Centauri b, and could cause the entire planet to glow green.”

Courtesy-Space

Alien Megastructure Around Star May Not Exist

October 13, 2017 by  
Filed under Around The Net

There’s a prosaic explanation for at least some of the weirdness of “Tabby’s star,” it would appear.

The bizarre long-term dimming of Tabby’s star — also known as Boyajian’s star, or, more formally, KIC 8462852 — is likely caused by dust, not a giant network of solar panels or any other “megastructure” built by advanced aliens, a new study suggests.

Astronomers came to this conclusion after noticing that this dimming was more pronounced in ultraviolet (UV) than infrared light. Any object bigger than a dust grain would cause uniform dimming across all wavelengths, study team members said

“This pretty much rules out the alien megastructure theory, as that could not explain the wavelength-dependent dimming,” lead author Huan Meng of the University of Arizona said in a statement. “We suspect, instead, there is a cloud of dust orbiting the star with a roughly 700-day orbital period.”

Strange brightness dips

KIC 8462852, which lies about 1,500 light-years from Earth, has generated a great deal of intrigue and speculation since 2015. That year, a team led by astronomer Tabetha Boyajian (hence the star’s nicknames) reported that KIC 8462852 had dimmed dramatically several times over the past half-decade or so, once by 22 percent.

No orbiting planet could cause such big dips, so researchers began coming up with possible alternative explanations. These included swarms of comets or comet fragments, interstellar dust and the famous (but unlikely) alien-megastructure hypothesis.

The mystery deepened after the initial Boyajian et al. study. For example, other research groups found that, in addition to the occasional short-term brightness dips, Tabby’s star dimmed overall by about 20 percent between 1890 and 1989. In addition, a 2016 paper determined that its brightness decreased by 3 percent from 2009 to 2013.

The new study, which was published online Tuesday (Oct. 3) in The Astrophysical Journal, addresses such longer-term events.

From January 2016 to December 2016, Meng and his colleagues (who include Boyajian) studied Tabby’s star in infrared and UV light using NASA’s Spitzer and Swift space telescopes, respectively. They also observed it in visible light during this period using the 27-inch-wide (68 centimeters) telescope at AstroLAB IRIS, a public observatory near the Belgian village of Zillebeke.

The observed UV dip implicates circumstellar dust — grains large enough to stay in orbit around Tabby’s star despite the radiation pressure but small enough that they don’t block light uniformly in all wavelengths, the researchers said.

The new study does not solve all of KIC 8462852’s mysteries, however. For example, it does not address the short-term 20 percent brightness dips, which were detected by NASA’s planet-hunting Kepler space telescope. (Kepler is now observing a different part of the sky during its K2 extended mission and will not follow up on Tabby’s star for the forseeable future.)

And a different study — led by Joshua Simon of the Observatories of the Carnegie Institution for Science in Pasadena, California — just found that Tabby’s star experienced two brightening spells over the past 11 years. (Simon and his colleagues also determined that the star has dimmed by about 1.5 percent from February 2015 to now.)

“Up until this work, we had thought that the star’s changes in brightness were only occurring in one direction — dimming,” Simon said in a statement. “The realization that the star sometimes gets brighter in addition to periods of dimming is incompatible with most hypotheses to explain its weird behavior.”

Courtesy-Space

Astronomers Discover Water Mystery On Mars

October 9, 2017 by  
Filed under Around The Net

A new examination of old data suggests that there might be ice hiding in the Martian equator, even though scientists previously thought that the substance couldn’t exist there.

Scientists uncovered an unexpected amount of hydrogen when looking at older data from NASA’s Mars Odyssey spacecraft dating back to between 2002 and 2009. At higher latitudes, hydrogen generally indicates buried water ice, but this was not believed possible at the equator, according to a statement from NASA.

If there is indeed water there, this would help with a future human mission to Mars, because it could mean the astronauts wouldn’t need to bring the substance with them for drinking, cooling equipment or watering plants, researchers said in the statement. Instead, the astronauts could live off the land to an extent, reducing the number of resources that need to be trucked (at higher cost) from Earth

Mars Odyssey’s first major discovery, in 2002, was also linked to water; the spacecraft found buried hydrogen at high latitudes, and the 2008 landing of the Phoenix Mars lander confirmed that there was water ice. However, at lower latitudes, measurements of hydrogen were explained as hydrated minerals (which other spacecraft have also observed). Researchers didn’t think water ice was thermodynamically stable in those areas.

For this new study, the researchers analyzed data collected using Mars Odyssey’s neutron spectrometer. The instrument is not designed to directly detect water, but by measuring neutrons, it can detect signatures of hydrogen, which can mark the presence of water or other hydrogen-bearing substances. 

The science team reduced the blurring or “noise” in Odyssey’s data using image-reconstruction techniques based on those used for other spacecraft and for medicine, according to the statement. This improved the spatial resolution of the data to 180 miles (290 kilometers), twice the previous resolution of 320 miles (520 km).

“It was as if we’d cut the spacecraft’s orbital altitude in half, and it gave us a much better view of what’s happening on the surface,” Jack Wilson, the study’s principal investigator and a postdoctoral researcher at the Johns Hopkins University Applied Physics Laboratory.

Their work focused on equatorial areas, particularly in zones around the Medusae Fossae formation, an area that includes material that is easy to erode. Previous observations from NASA’s Mars Reconnaissance Orbiter and the European Space Agency’s Mars Express orbiter suggested there might be volcanic deposits or water ice just below the surface. Scientists, however, were skeptical that it was water ice, because “if the detected hydrogen were buried ice within the top meter [3.3 feet] of the surface, there would be more than would fit into pore space in soil,” Wilson said.

The study’s scientists emphasized that more evidence is needed to conclude that the signature indeed comes from water ice. They’re not too sure how the water was preserved, they said; perhaps ice and dust flowing from the poles moved through the atmosphere when Mars had a steeper axis tilt than today. However, it’s been at least hundreds of thousands of years since those conditions existed, and the water ice deposited back then shouldn’t be around anymore, the researchers said. (This would be true even if, somehow, dust or a crust at the surface trapped the humidity underground, the scientists added.)

“Perhaps the signature could be explained in terms of extensive deposits of hydrated salts, but how these hydrated salts came to be in the formation is also difficult to explain,” Wilson said. “So, for now, the signature remains a mystery worthy of further study, and Mars continues to surprise us.”

Courtesy-Space

Astronomers Discover Prehistoric Lake On Mars Could Have Supported Life

October 6, 2017 by  
Filed under Around The Net

An up-close view of Mars’ rocky deposits by NASA’s Curiosity rover shows a changing climate in the planet’s ancient past that would have left the surface warm and humid enough to support liquid water — and possibly life. Evidence of an ancient lake points to the prospect of two unique habitats within its shores; the lower part of the lake was devoid of oxygen compared to an oxygen-rich upper half. 

In a recent paper published in the journal Science, Redox stratification of an ancient lake in Gale crater,” Stony Brook University geoscientist Joel Hurowitz and his colleagues used more than three years of data retrieved from the rover to paint a picture of ancient conditions at Gale Crater, the lowest point in a thousand kilometers. The site, a 150-mile kilometer crater formed during an impact around 3.8 billion years ago, once flowed with rivers ending in a lake. The sedimentary rocks laid down by these rivers and onto the lakebed tell the story of how the environment changed over time.

Curiosity landed on a group of sedimentary rocks known as the Bradbury group. The rover sampled a part of this group called the Sheepbed mudstones, as well as rocks from the Murray formation at the base of the 5-kilometer high peak at the center of the crater known as Mount Sharp. Both types of rocks were deposited in the ancient lake, but the Sheepbed rocks are older and occur lower in the stratigraphic layers of rocks. Comparing the two types of rocks can lead to interesting revelations about the paleoenvironment. 

Rocks that form at the same time in the same area can nevertheless display differences in composition and other characteristics. These different groupings are known as “facies” and the Murray formation is split into two facies. One is comprised mainly of hematite and phyllosilicate, and given the name HP, while the other is the magnetite-silicate facies, known as MS. 

“The two Murray facies were probably laid down at about the same time within different parts of the lake,” explained Hurowitz. “The former laid down in shallow water, and the latter in deeper water.”

The near-shore HP facies have thicker layers in the rocks compared to the thin layers of the deeper water MS facies. This difference in layer thickness is because the river flowing into the lake would have slowed down and dumped some of its sedimentary material at the lake shore. The flow would then have spread into the lake and dropped finer material into the deeper parts of the lake. 

Curiosity landed on rocks known as the Bradbury group. The Murray formation consist of younger rocks at the base of Mount Sharp. The height is exaggerated in the diagram.

The different mineralogy of the two facies was caused by the lake becoming separated into two layers. Ultraviolet (UV) radiation along with low levels of atmospheric oxygen penetrated the upper part of the lake and acted as oxidants on molecules in the water. These ions of iron (Fe2+) and manganese (Mn2+) were brought to the lake via seepage of groundwater through the lake floor.

When the UV and oxygen interacted with these, they lost electrons, meaning that they had become “oxidized.” The oxidized iron and manganese precipitated into minerals — hematite and manganese oxide — that eventually made up the rocks sampled by Curiosity in the HP facies. However, the UV and oxygen didn’t reach all the way to the lake floor, so the iron and manganese wasn’t oxidized in the deeper part of the lake, and instead became the mineral known as magnetite, making up the MS facies. 

The difference in oxidation of the two facies in the Murray formation due to differences in layers of the lake is known as redox stratification. Identifying redox stratification in the ancient lake shows that there were two completely different types of potential habitat available to any microbial life that might have been present.

The researchers also discovered that the Murray formation has a high concentration of salts, which provide clues relating to evaporation of the lake, and thus the end of the potential habitat. High salinity is a result of water evaporating and leaving salts behind. However, evaporation leaves other tell-tale signs such as desiccation cracks — similar to what you see when mud dries and cracks — and none of these signs appear in the Murray formation. This indicates that the evaporation occurred at a later period of time and that the salts seeped through layers overlying the Murray formation before becoming deposited in the Murray rocks. 

“Curiosity will definitely be able to examine the rocks higher up in the stratigraphy to determine if lake evaporation influenced the rocks deposited in it,” said Hurowitz. “In fact, that’s exactly what the rover is doing as we speak at the area known as Vera Rubin Ridge.”

Once Curiosity examines these rocks, it will be able to confirm that the salts found in the Murray formation came from a later period of evaporation, and therefore no significant evaporation occurred during the time that the Murray formation was deposited, meaning the environment would have been stable enough to support possible life forms.

The inflowing river deposits thicker material (clastics) close to the lake shore, and finer material towards the deeper part of the lake. The incoming UV and O2 oxidizes the iron and manganese in the upper part

Another result of the research is evidence of climate change. The older Sheepbed formation shows very little evidence of chemical weathering compared to the Murray formation. The change to substantial chemical weathering in the younger rocks indicates that the climate likely changed from cold, arid conditions to a warm, wet one. 

“The timing of this climate shift is not something we can tell for sure because we haven’t seen the Sheepbed member and the Murray formation in contact with each other,” said Hurowitz. “If we had, then we might be able to tell if the change in their chemical and mineralogical properties were abrupt (indicating rapid climate change) or gradual. At best, what we can say is that the rocks that we examined were likely deposited over a timespan of tens of thousands of years to as much as around 10 million years.”

The cause of the climate change on Mars is still a matter of debate. If the climate changed in a short period of time, it could have been due to short-term variations or an asteroid impact. A slower change in climate could have been the result of changes in the obliquity cycle of the planet.

The climate change indicated in the rocks shows that the ancient Martian environment would have been warm and humid enough to sustain liquid water on the surface. The redox stratification of the lake as revealed by the different mineralogy in the Murray formation shows that there would have been two different environments within the lake itself. If microbial life was present on Mars at this time, the different potentially habitable niches could have encouraged diversity with anaerobic forms possibly living in the lower depths of the lake. 

“I’m not sure that this was something we would have predicted if we hadn’t had the opportunity to examine Gale’s rock record up close and personal,” adds Hurowitz.

Courtesy-Space

 

Astronomers Find Carbon Star With Red Glowing Bubble

September 28, 2017 by  
Filed under Around The Net

Gorgeous new imagery shows the enormous, glowing bubble that a strange, dying red star has blown around itself.

The huge star, known as U Antliae, lies about 900 light-years from Earth, in the southern constellation Antlia (the Air Pump). U Antliae has burned all the hydrogen and helium in its core and has therefore moved on to the “asymptotic giant branch” (AGB), the last major step in the life cycle of a sun-like star before it becomes superdense white dwarf. 

AdvertisementA few millennia ago, U Antliae erupted in a spasm of activity that generated a big bubble, a surprisingly thin structure that astronomers have now studied using the European Southern Observatory’s Atacama Large Millimeter/submillimeter Array (ALMA), a network of radio telescopes in northern Chile.

“Around 2,700 years ago, U Antliae went through a short period of rapid mass loss,” ESO officials wrote in a statement. “During this period of only a few hundred years, the material making up the shell seen in the new ALMA data was ejected at high speed. Examination of this shell in further detail also shows some evidence of thin, wispy gas clouds known as filamentary substructures.”

ALMA captured the bubble in multiple wavelengths of light, producing a 3D “data cube” that researchers have mined in detail. For example, the imagery shows gases in the bubble moving toward or away from the observer at different speeds, ESO officials said.

This image was created from ALMA data on the red carbon star U Antliae and its surrounding shell of material. The colors show the motion of the glowing material in the shell along the line of sight to the Earth. Blue material lies between us and the central star, and is moving toward us. Red material around the edge is moving away from the star, but not toward Earth. (For clarity, this view does not include the material on the far side of the star, which is receding from us in a symmetrical manner.)

Analyzing such stellar bubbles could help astronomers better understand the evolution of stars and galaxies, ESO officials added.

“Shells such as the one around U Antliae show a rich variety of chemical compounds based on carbon and other elements,” the officials wrote in the same statement. “They also help to recycle matter and contribute up to 70 percent of the dust between stars.”

The new ALMA imagery is part of a study, led by Franz Kerschbaum of the University of Vienna, that has been accepted for publication in the journal Astronomy & Astrophysics.

Courtesy-Space 

Astronomers Ponder The Role Of Physics In Life

September 25, 2017 by  
Filed under Around The Net

Understanding the origin of life is arguably one of the most compelling quests for humanity. This quest has inevitably moved beyond the puzzle of life on Earth to whether there’s life elsewhere in the universe. Is life on Earth a fluke? Or is life as natural as the universal laws of physics?

Jeremy England, a biophysicist at the Massachusetts Institute of Technology, is trying to answer these profound questions. In 2013, he formulated a hypothesis that physics may spontaneously trigger chemicals to organize themselves in ways that seed “life-like” qualities.

Now, new research by England and a colleague suggests that physics may naturally produce self-replicating chemical reactions, one of the first steps toward creating life from inanimate substances.

This might be interpreted as life originating directly from the fundamental laws of nature, thereby removing luck from the equation. But that would be jumping the gun.

Life had to have come from something; there wasn’t always biology. Biology is born from the raw and lifeless chemical components that somehow organized themselves into prebiotic compounds, created the building blocks of life, formed basic microbes and then eventually evolved into the spectacular array of creatures that exist on our planet today.  

“Abiogenesis” is when something nonbiological turns into something biological and England thinks thermodynamics might provide the framework that drives life-like behavior in otherwise lifeless chemicals. However, this research doesn’t bridge life-like qualities of a physical system with the biological processes themselves, England said.

“I would not say I have done anything to investigate the ‘origin of life’ per se,” England told Live Science. “I think what’s interesting to me is the proof of principle – what are the physical requirements for the emergence of life-like behaviors?”

Self-organization in physical systems

When energy is applied to a system, the laws of physics dictate how that energy dissipates. If an external heat source is applied to that system, it will dissipate and reach thermal equilibrium with its surroundings, like a cooling cup of coffee left on a desk. Entropy, or the amount of disorder in the system, will increase as heat dissipates. But some physical systems may be  sufficiently out of equilibrium that they “self-organize” to make best use of an external energy source, triggering interesting self-sustaining chemical reactions that prevent the system from reaching thermodynamic equilibrium and thus maintaining an out-of-equilibrium state, England speculates. (It’s as if that cup of coffee spontaneously produces a chemical reaction that sustains a hotspot in the center of the fluid, preventing the coffee from cooling to an equilibrium state.) He calls this situation “dissipation-driven adaptation” and this mechanism is what drives life-like qualities in England’s otherwise lifeless physical system.

A key life-like behavior is self-replication, or (from a biological viewpoint) reproduction. This is the basis for all life: It starts simple, replicates, becomes more complex and replicates again. It just so happens that self-replication is also a very efficient way of dissipating heat and increasing entropy in that system.

In a study published July 18 in the journal Proceedings of the National Academy of Sciences,  England and co-author Jordan Horowitz tested their hypothesis. They carried out computer simulations on a closed system (or a system that doesn’t exchange heat or matter with its surroundings) containing a “soup” of 25 chemicals. Although their setup is very simple, a similar type of soup may have pooled on the surface of a primordial and lifeless Earth. If, say, these chemicals are concentrated and heated by an external source – a hydrothermal vent, for example – the pool of chemicals would need to dissipate that heat in accordance with the second law of thermodynamics. Heat must dissipate and the entropy of the system will inevitably increase.

Under certain initial conditions, he found that these chemicals may optimize the energy applied to the system by self-organizing and undergoing intense reactions to self-replicate. The chemicals fine-tuned themselves naturally. These reactions generate heat that obeys the second law of thermodynamics; entropy will always increase in the system and the chemicals would self-organize and exhibit the life-like behavior of self-replication.

“Essentially, the system tries a bunch of things on a small scale, and once one of them starts experiencing positive feedback, it does not take that long for it to take over the character of organization in the system,” England told Live Science.

This is a very simple model of what goes on in biology: chemical energy is burned in cells that are – by their nature – out of equilibrium, driving the metabolic processes that maintain life. But, as England admits, there’s a big difference between finding life-like qualities in a virtual chemical soup and life itself.

Sara Imari Walker, a theoretical physicist and astrobiologist at Arizona State University who was not involved in the current research, agrees.

“There’s a two-way bridge that needs to be crossed to try to bridge biology and physics; one is to understand how you get life-like qualities from simple physical systems and the other is to understand how physics can give rise to life,” Imari Walker told Live Science. “You need to do both to really understand what properties are unique to life and what properties are characteristic of things that you consider to be almost alive […] like a prebiotic system.”

Emergence of life beyond Earth?

Before we can even begin to answer the big question of whether these simple physical systems may influence the emergence of life elsewhere in the universe, it would be better to understand where these systems exist on Earth first.

“If, when you say ‘life,’ you mean stuff that is as stunningly impressive as a bacterium or anything else with polymerases and DNA, my work doesn’t yet tell us anything about how easy or difficult it is to make something that complex, so I shouldn’t speculate about what we’d be likely to find elsewhere than Earth,”  England said. (Polymerases are proteins that assemble DNA and RNA.)

This research doesn’t specifically identify how biology emerges from nonbiological systems, only that in some complex chemical situations, surprising self-organization occurs. These simulations do not consider other life-like qualities – such as adaptation to environment or reaction to stimuli. Also, this thermodynamics test on a closed system does not consider the role of information reproduction in life’s origins, said Michael Lässig, a statistical physicist and quantitative biologist at the University of Cologne in Germany.

“[This] work is indeed a fascinating result on non-equilibrium chemical networks but it is still a long way from a physics explanation of the origins of life, which requires the reproduction of information,” Lässig, who was not involved in the research, told Live Science.

There’s a critical role for information in living systems, added Imari Walker. Just because there appears to be natural self-organization exhibited by a soup of chemicals, it doesn’t necessarily mean living organization.

“I think there’s a lot of intermediate stages that we have to get through to go from simple ordering to having a full-on information processing architecture like a living cell, which requires something like memory and hereditary,” said Imari Walker. “We can clearly get order in physics and non-equilibrium systems, but that doesn’t necessarily make it life.”

To say England’s work could be the “smoking gun” for the origin of life is premature, and there are many other hypotheses as to how life may have emerged from nothing, experts said. But it is a fascinating insight into how physical systems may self-organize in nature. Now that researchers have a general idea about how this thermodynamic system behaves, it would be a nice next step to identify sufficiently out-of-equilibrium physical systems that naturally occur on Earth, England said.

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Astronomers Find Titanium Oxide On Aline Planet

September 22, 2017 by  
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For the first time ever, titanium oxide has been spotted in an exoplanet’s skies, a new study reports.

Astronomers using the European Southern Observatory’s Very Large Telescope (VLT) in Chile detected the substance in the atmosphere of WASP-19b, a huge, scorching-hot planet located 815 light-years from Earth.

The presence of titanium oxide in the atmosphere of WASP-19b can have substantial effects on the atmospheric temperature structure and circulation,” study co-author Ryan MacDonald, an astronomer at the University of Cambridge in England, said in a statement.  

One possible effect is “thermal inversion.” If enough titanium oxide is present, the stuff can keep heat from entering or exiting an atmosphere, causing upper layers to be hotter than lower layers, researchers said. (This phenomenon occurs in Earth’s stratosphere, but the culprit is ozone, not titanium oxide.)

Artist’s illustration showing the exoplanet WASP-19b, whose atmosphere contains titanium oxide. In large enough quantities, titanium oxide can prevent heat from entering or escaping an atmosphere, leading to a “thermal inversion” in which temperatures are higher in the upper atmosphere than lower down.

WASP-19b is a bizarre world about the mass of Jupiter. The alien planet lies incredibly close to its host star, completing one orbit every 19 hours. As a result, WASP-19b’s atmospheric temperatures are thought to hover around 3,600 degrees Fahrenheit (2,000 degrees Celsius).

The research team — led by Elyar Sedaghati of the European Southern Observatory, the German Aerospace Center and the Technical University of Berlin — studied WASP-19b for more than a year using the VLT’s refurbished FORS2 instrument. These observations allowed them to determine that small amounts of titanium oxide, along with water and wisps of sodium, swirl around in the exoplanet’s blistering air.

“Detecting such molecules is, however, no simple feat,” Sedaghati said in the same statement. “Not only do we need data of exceptional quality, but we also need to perform a sophisticated analysis. We used an algorithm that explores many millions of spectra spanning a wide range of chemical compositions, temperatures, and cloud or haze properties in order to draw our conclusions.”

In addition to shedding new light on WASP-19b, the new study — which was published online today (Sept. 13) in the journal Nature — should improve researchers’ modeling of exoplanet atmospheres in general, team members said.

“To be able to examine exoplanets at this level of detail is promising and very exciting,” said co-author Nikku Madhusudhan, also of the University of Cambridge. 

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With Boron On Mars Prove Life Once Existed

September 21, 2017 by  
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NASA’s Mars rover Curiosity has discovered boron in Gale Crater — new evidence that the Red Planet may have been able to support life on its surface in the ancient past.

Boron is a very interesting element to astrologists; on Earth, it’s thought to stabilize the sugary molecule ribose. Ribose is a key component of ribonucleic acid (RNA), a molecule that’s present in all living cells and drives metabolic processes. But ribose is notoriously unstable, and to form RNA, it is thought that boron is required to stabilize it. When dissolved in water, boron becomes borate, which, in turn, reacts with ribose, making RNA possible.

In a new study published in the journal Geophysical Research Letters, researchers analyzed data gathered by Curiosity’s ChemCam (Chemistry and Camera) instrument, which zaps rocks with a powerful laser to see what minerals they contain. ChemCam detected the chemical fingerprint of boron in calcium-sulfate mineral veins that have been found zigzagging their way through bedrock in Gale Crater, the 96-mile-wide (154 kilometers) crater that the rover is exploring. These veins were formed by the presence of ancient groundwater, meaning the water contained borate.

The find raises exciting possibilities, the researchers said.

“Because borates may play an important role in making RNA — one of the building blocks of life — finding boron on Mars further opens the possibility that life could have once arisen on the planet,” study lead author Patrick Gasda, a postdoctoral researcher at Los Alamos National Laboratory in New Mexico, said in a statement. 

“Borates are one possible bridge from simple organic molecules to RNA,” he added. “Without RNA, you have no life. The presence of boron tells us that, if organics were present on Mars, these chemical reactions could have occurred.”

Scientists have long hypothesized that the earliest “proto-life” on Earth emerged from an “RNA World,” where individual RNA strands containing genetic information had the ability to copy themselves. The replication of information is one of the key requirements for basic lifelike systems. Therefore, the detection of boron on Mars, locked in calcium-sulfate veins that we know were deposited by ancient water, shows that borates were present in water “0 to 60 degrees Celsius (32 to 140 degrees Fahrenheit) and with neutral-to-alkaline pH,” the researchers said.

“We detected borates in a crater on Mars that’s 3.8 billion years old, younger than the likely formation of life on Earth,” Gasda added. “Essentially, this tells us that the conditions from which life could have potentially grown may have existed on ancient Mars, independent from Earth.”

Since landing on Mars in 2012, Curiosity has uncovered compelling evidence that the planet used to be a far wetter place than it is now. For example, the rover has found evidence of a lake-and-stream system inside Gale Crater that lasted for long stretches in the distant past. And, by climbing the slopes of Mount Sharp — the 3.4-mile-high (5.5 km) mountain in the crater’s center — Curiosity has been able to examine various layers of sedimentary minerals that formed in the presence of ancient water. 

These studies are helping scientists gain a better understanding of how long these minerals were dissolved in the water, where they were deposited and, ultimately, how they impacted the habitability of the Red Planet. The detection of boron is another strand of evidence supporting the idea that ancient life might have existed on our neighboring planet.

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Can The James Webb Telescope Find Life In Our Solar System

September 18, 2017 by  
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The soon-to-launch James Webb Space Telescope will turn its powerful eye on two of the solar system’s top candidates for hosting alien life: the icy moons Enceladus and Europa, the agency confirmed in a statement this month.

Both Europa (a moon of Jupiter) and Enceladus (a moon of Saturn) are thought to possess subsurface oceans of liquid water beneath thick outer layers of ice. Both moons have also shown evidence of enormous plumes of liquid shooting up through cracks in the surface ice; these plumes could be caused by subsurface geysers, which could provide a source of heat and nutrients to life-forms there, scientists have said.

“We chose these two moons because of their potential to exhibit chemical signatures of astrobiological interest,” said Heidi Hammel, executive vice president of the Association of Universities for Research in Astronomy (AURA), who is leading an effort to use the telescope to study objects in Earth’s solar system.  

The James Webb Space Telescope, nicknamed “Webb,” will capture infrared light, which can be used to identify objects that generate heat but are not hot enough to radiate light (including humans, which is why many night-vision systems utilize infrared light). Researchers are hoping that Webb can help to identify regions on the surfaces of these moons where geologic activity, such as plume eruptions, are taking place. 

Enceladus’ plumes were studied in detail by the Cassini probe at Saturn. The spacecraft spotted hundreds of plumes, and even flew through some of them and sampled their composition. Europa’s plumes were spotted by the Hubble Space Telescope, and researchers know far less about them than those on Europa.

“Are they made of water ice? Is hot water vapor being released? What is the temperature of the active regions and the emitted water?” Geronimo Villanueva, lead scientist on the Webbobservation of Europa and Enceladus, said in the statement. “Webb telescope’s measurements will allow us to address these questions with unprecedented accuracy and precision.”

Webb’s observations will help pave the way for the Europa Clipper mission, a $2 billion orbital mission to the icy moon. Scheduled to launch in the 2020s, Europa Clipper will search for signs of life on Europa. The observations with Webb could identify areas of interest for the Europa Clipper mission to investigate, according to the statement.

As seen by Webb, the Saturn moon Enceladus will appear about 10 times smaller than Europa, so scientists will not be able to capture high-resolution views of Enceladus’ surface, according to the statement. However, Webb can still analyze the molecular composition of Enceladus’ plumes. 

But it’s also possible that the observations won’t catch a plume erupting from Europa’s surface; scientists don’t know how frequently these geysers erupt, and the limited observing time with Webb may not coincide with one of them. The telescope can detect organics — elements such as carbon that are essential to the formation of life as we know it — in the plumes. However, Villanueva cautioned that Webb does not have the power to directly detect life-forms in the plumes.

Webb is set to launch in 2018 and will orbit the sun at the L2 Lagrange point, which is about one million miles (1.7 million km) farther from the sun than the Earth’s orbit around the sun. The telescope will provide high-resolution views of both the very distant and very nearby universe. Scientists have already begun submitting ideas for objects or regions that should be observed using Webb’s powerful eye, and Europa and Enceladus are among the objects that are now guaranteed observing time.

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Project Blue Telescope Goes CrowdFunding

September 15, 2017 by  
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The private space telescope initiative Project Blue launched a new crowdfunding campaign Sept. 6 in a second attempt to raise money for its mission to directly image Earth-like exoplanets. 

The initiative aims to launch a small space telescope into low-Earth orbit. The telescope will spy on our interstellar neighbor Alpha Centauri and image any Earth-like planets that might orbit the star system.

In support of Project Blue, BoldlyGo Institute and numerous organizations, including the SETI (Search for Extraterrestrial Intelligence) Institute, the University of Massachusetts Lowell and Mission Centaur, launched an IndieGoGo campaign to raise $175,000 over the next two months. The funds will be used to establish mission requirements, design the initial system architecture and test its capability for detecting exoplanets. Project leaders will also begin looking for potential partners who could manufacture parts of the space telescope, representatives said in a statement. 

“We’re very excited to pursue such an impactful space mission and, as a privately-funded effort, to include a global community of explorers and space science advocates in Project Blue from the beginning,” Jon Morse, CEO of BoldlyGo Institute, said in the statement.

Last year, Project Blue organizers attempted to raise $1 million through the crowdfunding platform Kickstarter, but the campaign was canceled after only $335,597 was contributed and Project Blue received none of the funds (as is Kickstarter’s policy). 

With the IndieGoGo campaign, however, the organizers have a more flexible goal and will be able to keep all contributions from supporters, even if the initial goal of $175,000 is not reached. So far, more than $45,000 has been raised through the campaign.

The neighboring star system Alpha Centauri is located only 4.37 light-years from Earth, making it a target for scientific research. Project Blue estimates it will take about $50 million to build the special-purpose telescope, which is planned to launch in 2021. 

The small space telescope will use a specialized coronagraph to block the bright glare of Alpha Centauri’s stars and detect planets that may be orbiting there. One planet, Proxima b, has already been detected around Proxima Centauri. 

However, Proxima b was discovered indirectly, by measuring the planet’s gravitational effect on its host star. Instead, the Project Blue telescope will be designed to directly image Earth-like planets in Alpha Centauri’s neighborhood.

 

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Do Trappist-1 Planets Have Enough Water For Alien Life

September 11, 2017 by  
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The new study looks at how much ultraviolet (UV) radiation is received by each of the planets, because this could affect how much water the worlds could sustain over billions of years, according to the study. Lower-energy UV light can break apart water molecules into hydrogen and oxygen atoms on a planet’s surface, while higher-energy UV light (along with X-rays from the star) can heat a planet’s upper atmosphere and free the separated hydrogen and oxygen atoms into space, according to the study. (It’s also possible that the star’s radiation destroyed the planets’ atmospheres long ago.)

The researchers measured the amount of UV radiation bathing the TRAPPIST-1 planets using NASA’s Hubble Space Telescope, and in their paper they estimate just how much water each of the worlds could have lost in the 8 billion years since the system formed.

It’s possible that the six innermost planets (identified by the letters b, c, d, e, f and g), pelted with the highest levels of UV radiation, could have lost up to 20 Earth-oceans’ worth of water, according to the paper. But it’s also possible that the outermost four planets (e, f, g and h — the first three of which are in the star’s habitable zone) lost less than three Earth-oceans’ worth of water.

If the planets had little or no water to start with, the destruction of water molecules by UV radiation could spell the end of the planets’ habitability. But it’s possible that the planets were initially so rich in liquid water that, even with the water loss caused by UV radiation, they haven’t dried up,  according to one of the study’s authors, Michaël Gillon, an astronomer at the University of Liège in Belgium. Gillon was also lead author on two studies that first identified the seven TRAPPIST-1 planets.

“It is very likely that the planets formed much farther away from the star [than they are now] and migrated inwards during the first 10 million years of the system,” Gillon told Space.com in an email.

Farther away from their parent star, the planets might have formed in an environment rich in water ice, meaning the planets could have initially had very water-rich compositions.

“We’re talking about dozens, and maybe even hundreds of Earth-oceans, so a loss of 20 Earth-oceans wouldn’t matter much,” Gillon said. “What our results show is that even if the outer planets were initially quite water-poor like the original Earth, they could still have some water on their surfaces.”

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Was Proxima b Stripped Of It’s Atmosphere Eons Ago

September 7, 2017 by  
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The nearby alien planet Proxima b may have lost the ability to support life long ago, a new study suggests.

If Earth had formed where Proxima b orbits — quite close to a red dwarf star — our planet’s atmosphere would likely have been stripped away by intense stellar radiation fairly quickly, the study found.

“Things can get interesting if an exoplanet holds on to its atmosphere, but Proxima b’s atmospheric loss rates here are so high that habitability is implausible,” co-author Jeremy Drake, an astrophysicist at the Harvard-Smithsonian Center for Astrophysics, said in a statement. “This questions the habitability of planets around such red dwarfs in general.”

Proxima b circles the red dwarf Proxima Centauri, which lies just 4.2 light-years from the sun. The roughly Earth-size exoplanet completes one lap around its host star once every 11 Earth days. But, because Proxima Centauri is much dimmer than the sun, this tight orbit puts Proxima b within the habitable zone — the region where liquid water could exist on a planet’s surface. 

This proximity also puts the planet in danger, however. Red dwarfs tend to be quite active, especially in their youths. Charged particles pour out from these stars into space, and the closer a planet orbits to such a star, the more intensely it gets hit by damaging radiation. 

High-energy UV light can knock electrons off molecules in a planet’s atmosphere, producing charged particles (also known as ions). Some of these newly liberated electrons can be energetic enough to escape the planet’s gravity, pulling particles of the opposite charge with them into space.

This atmosphere-stripping stellar activity is one reason many scientists argue that most planets around red dwarfs are not habitable. Because red dwarfs make up roughly three-quarters of the stars in the Milky Way, most of the galaxy’s rocky planets may receive too much radiation for life to evolve.

Planets can have a variety of shields against radiation. One possibility is a thick atmosphere, which can absorb the bulk of radiation hitting a planet. Another is a magnetic field, which can funnel charged particles away from the planet. But magnetic fields aren’t always helpful. 

“The magnetic poles of a planet can be connected to the stellar wind, which provides a pathway for the upper, ionized region of the atmosphere to escape,” said Katherine Garcia-Sage, lead author of the new study and a space scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.

“Energy from the stellar wind is also redirected to the magnetic poles, providing extra energy for escape at these same regions where ions and electrons are able to leave the planet and enter interplanetary space,” told Space.com via email.

So, the same magnetic field that shields a planet can also help funnel away part of its atmosphere.  

To investigate what might be happening with Proxima b, Garcia-Sage and her colleagues did some computer modeling. Their models put an Earth twin — an Earth-size world with an Earth-like magnetic field — at Proxima b’s spot and then buffeted the planet with the appropriate radiation (levels of which were determined using nearly 40 years of observations of Proxima Centauri).

“This was a simple calculation based on average activity from the host star,” Garcia-Sage said in the same statement. “It doesn’t consider variations like extreme heating in the star’s atmosphere or violent stellar disturbances to the exoplanet’s magnetic field — things we’d expect to provide even more ionizing radiation and atmospheric escape.”

Despite the relatively conservative radiation dose, the modeled planet didn’t fare well, the researchers found. Assuming high atmospheric temperatures and a completely open magnetic field, Proxima b could lose an Earth-equivalent atmosphere in only 100 million years, an eye-blink in the 4-billion-year lifetime of the planet, the researchers said. Even with the lowest temperatures and a closed magnetic field, the atmosphere would be stripped in 2 billion years.

Of course, these results assume an Earth-like magnetic field. A stronger or weaker magnetic field could produce different timescales, the scientists said.

“It is not immediately obvious which quantities contribute to a planetary magnetic field and to its strength,” said Chuanfei Dong, a researcher at Princeton University. Dong, who was not involved in the project, studies exoplanet atmospheres.

Candidate contributors include a planet’s radius, conductivity, density and core rotation rate, Dong said, and none of these quantities are known for Proxima b. Because of how the planet was detected, scientists have direct measurements of its mass but not its radius. That means they cannot directly calculate Proxima b’s density, which would yield insights about the planet’s core. Instead, researchers rely on previous studies that link a planet’s mass with its radius.

“The radius of the planet can affect the radius of the electrically conducting fluid core, so it can affect the development and strength of its magnetic field,” Dong told Space.com.

The distance between a planet and its star, and the time the planet takes to orbit, can also play important roles in determining the magnetic field strength, Dong said. That’s due in part to the phenomenon called tidal locking, in which one side of a world permanently faces its star — a common feature of tightly orbiting worlds such as those in the habitable zones of red dwarfs.

Though the new results — which were published last month in The Astrophysical Journal Letters — don’t bode well for the prospect of life on Proxima b, not all hope is lost, Dong said. Geological processes such as volcanic activity could help replenish a planet’s atmosphere, he said. 

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Astronomers Capture First Star Beyond The Sun

August 31, 2017 by  
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A new photo of the red “supergiant”Antares is the best ever captured of a star other than the sun, researchers said.

The image shows Antares’ tumultuous surface and reveals unexpected turbulence in its atmosphere, hinting at some mysterious process that is churning away violently inside the stellar mass, the scientists added.

Located nearly 620 light-years from Earth in the constellation of Scorpio, Antares is a puffy stellar monster, with a mass and diameter 12 times and 700 times that of our sun, respectively. Antares is therefore one of the largest and brightest stars known in our galaxy. It is also nearing the end of its life; astronomers estimate that it will explode as a supernova in just a few thousand years.

Now, using the European Southern Observatory’s Very Large Telescope Interferometer (VLTI) in Chile, astronomers have resolved the turbulent structure in the star’s outermost layers, revealing, for the first time, detail on a distant star’s surface and, possibly, filling in the gaps of our knowledge as to how massive stars die.

“How stars like Antares lose mass so quickly in the final phase of their evolution has been a problem for over half a century,” Keiichi Ohnaka, of the Universidad Católica del Norte in Chile, said in a statement. 

“The VLTI is the only facility that can directly measure the gas motions in the extended atmosphere of Antares — a crucial step towards clarifying this problem,” added Ohnaka, detailing the new finds that waslast week “The next challenge is to identify what’s driving the turbulent motions.”

The VLTI consists of up to four telescopes — a combination of 26.9-foot (8.2 meters) “Unit Telescopes” and smaller 5.9-foot (1.8 m) “Auxiliary Telescopes” — that combine their collected infrared light via interferometry to create a “virtual” telescope 660 feet (200 m) wide. Very high angular resolution of distant objects can therefore be attained, allowing the dramatic, bubbling surface of Antares to be studied in detail. 

Using an instrument called AMBER (Astronomical Multi-BEam combineR), Ohnaka’s team was able to measure the speed of plasma bubbling up from Antares’ interior at different positions and compare these speeds with the average speed of plasma across the whole of the star. From these data, a map of the relative speed of atmospheric gases over the star’s disk could be created. This is the first time that such a map has been created for any star apart from the sun, study team members said.

Immediately, the researchers uncovered a surprise: There appears to be turbulent, low-density gas erupting much farther out from the star than theoretical models predict. Usually, in stars like our sun, convection flows of superheated gases bubble up from near the stars’ cores to the surface, much like the convection flow of water in a boiling kettle. But convection cannot explain Antares’ strange atmosphere, and the researchers conclude that, for the atmospheres of red supergiants, there must be another — as yet unknown — process that drives the motion of material.

Ohnaka is hopeful that the observational techniques demonstrated on Antares may be applied to other stars to see how their atmospheres are structured, perhaps revealing the mystery that drives these turbulent motions. 

“Our work brings stellar astrophysics to a new dimension and opens an entirely new window to observe stars,” he said.

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Is “Opportunity” The Longest Running Rover On Mars

August 24, 2017 by  
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Opportunity is a rover that has been working on Mars since January 2004. Originally intended to last 90 days, the machine is still trekking after 13 years on the Red Planet. In 2015, it passed a driving milestone, reaching more than a marathon’s worth of distance (26.2 miles, or 42.1 kilometers) – and the rover keeps racking up driving time.

Lately, however, it has been showing its age. In 2014 and early 2015, NASA made several attempts to restore Opportunity’s flash memory capabilities after the rover experienced problems. Flash memory allows the rover to store information even when it is powered off. In 2015, NASA decided to continue most operations with random-access memory instead, which keeps data only when the power in the rover is on. At the time, NASA said the only change to operations will be requiring Opportunity to send high-priority data right away, as it cannot be stored if the rover is turned off. 

That said, the mission has been extremely productive on the Red Planet. Opportunity has explored two large craters — Victoria and Endeavour — among many other locations. Along the way, the rover has found multiple signs of water — while surviving a sand trap and bad dust storm.

Making an orphan’s dream come true

Opportunity and its twin rover, Spirit, received their names from 9-year-old Sofi Collis. She was the winner of a naming contest NASA held (with assistance from the Planetary Society and sponsorship from Lego) to find monikers for the Mars Exploration Rovers. Siberian-born Collis was adopted at age 2 and came to live with her new family in Scottsdale, Arizona.

“I used to live in an orphanage,” Collis wrote in her winning essay. “It was dark and cold and lonely. At night, I looked up at the sparkly sky and felt better. I dreamed I could fly there. In America, I can make all my dreams come true. Thank you for the ‘Spirit’ and the ‘Opportunity.'”

The Mars Exploration Rovers launched in 2003 on a 283-million-mile (455.4 million kilometers) journey to hunt for water on Mars. The $800-million cost for the two of them covered a suite of science instruments. Site survey tools included a panoramic camera, as well as a mini-thermal emission spectrometer that was supposed to search for signs of heat. Each rover also had a small arm with tools such as spectrometers and a microscopic imager.

Cruise to Mars

Opportunity left Earth July 7, 2003, aboard a Delta II rocket en route to a landing site at the Martian equator called Meridiani Planum. NASA was intrigued by a layer of hematite that the orbiting Mars Global Surveyor spotted from above. As hematite (an iron oxide) often forms in a spot that had liquid water, NASA was curious about how the water got there in the first place and where the water went.

The 384-pound rover made its final approach to Mars on Jan. 25, 2004. It plowed through the Martian atmosphere, popped out a parachute and then vaulted to the surface in a cocoon of airbags.

Opportunity rolled to a stop inside a shallow crater just 66 feet (20 meters) across, delighting scientists as the first pictures beamed back from the Red Planet. “We have scored a 300-million mile interplanetary hole-in-one,” quipped Cornell University’s Steve Squyres, principal investigator for the rover’s science instruments, in a press release in the days after the landing.

Early sols of science

Opportunity and Spirit (which had landed successfully three weeks earlier, on Jan. 3, 2004) had a primary goal to “follow the water” during their time on Mars. They would hunt for any environments that showed evidence of water activity, particularly looking for minerals that may have been left behind after water came through.

Both rovers met that goal quickly. In early March, just six weeks after landing, Opportunity identified a rock outcrop that showed evidence of a liquid past. The rocks at “Guadalupe” had sulfates as well as crystals inside of niches, which are both signs of water. Spirit found water evidence of its own that same week.

Two weeks later, Opportunity found hematite inside some small spheres that NASA dubbed “blueberries” because of their size and shape. Using a spectrometer, Opportunity found evidence of iron inside a group of berries when comparing it to the bare, underlying rock.

The month wasn’t yet over when Opportunity discovered more evidence of water, this time from images of a rock outcrop that probably formed from a deposit of saltwater in the ancient past. Chlorine and bromine found in the rocks helped solidify the theory.

It was a positive start to Opportunity’s mission — and it hadn’t even left the crater where it had landed yet. Before Opportunity’s 90-day prime mission was over, the golf-cart size rover clambered out of Eagle Crater and ventured to its next science target about half a mile away: Endurance Crater. It spotted more water signs there in October.

One of Opportunity’s most dangerous moments came in 2005, when the rover was mired in the sand for five weeks. NASA had put the rover into a “blind drive” on April 26, 2005, meaning the rover was not checking for obstacles as it went. Opportunity then plowed into a 12-inch-high (30 cm) sand dune, where the six-wheeled rover initially had trouble getting out.

To save the stranded rover, NASA ran tests on a model of the rover in a simulated Martian “sandbox” at the Jet Propulsion Laboratory. Based on what they learned in the sandbox, the rover drivers then sent a series of commands to Opportunity. It took the rover about 629 feet (191 meters) of wheel rotations before it was able to move forward three feet, but it cut itself free in early June 2005.

NASA chose to move the rover forward in more careful increments, which was especially important because Opportunity lost the full use of its right-front wheel (because of a seized steering motor) just days before it got stuck in the sand. The rover could still move around just fine with its other three steerable wheels, NASA said.

Opportunity’s experience in the sand came in handy in October 2005, when NASA detected unusual traction problems on Sol 603. Just 16 feet into a planned 148-foot drive, a slip check system on board automatically stopped the rover when it went past a programmed limit. Two Martian days later, Opportunity backed itself out of the problem and kept on going.

Victoria Crater

In late September 2006, Opportunity wheeled up to Victoria Crater after 21 months on the road. It circled the rim for a few months snapping pictures and getting a close look at some layered rocks surrounding the crater. NASA then made a gutsy decision in June 2007 to take Opportunity inside the crater. It was a risk to the rover as it might not have been able to climb up again, but NASA said the science was worth it.

“The scientific allure is the chance to examine and investigate the compositions and textures of exposed materials in the crater’s depths for clues about ancient, wet environments,” NASA stated in a press release. “As the rover travels farther down the slope, it will be able to examine increasingly older rocks in the exposed walls of the crater.”

The trek down was interrupted by a severe dust storm in July 2007. Opportunity’s power-generating capabilities dropped by 80 percent in only one week as its solar panels became covered in dust. Late in the month, Opportunity’s power dipped to critical levels. NASA worried the rover would stop working, but Opportunity pulled through.

It wasn’t until late August that the skies cleared enough for Opportunity to resume work and head into the crater. Opportunity spent about a year wandering through Victoria Crater, getting an up-close look at the layers on the bottom and figuring that these were likely shaped by water.

Opportunity climbed out successfully in August 2008 and began a gradual journey to Endeavour, an incredible 13 miles (21 km) away. It took about three years to get there, as the rover was stopping to look at interesting science targets on the way. But Opportunity successfully arrived in August 2011.

Opportunity’s water history examinations continued at Endeavour, with one example being a 2013 probe of a rock called “Esperance.” The rock not only has clay minerals produced by water, but there was enough of the liquid to “flush out ions set loose by those reactions,” stated Opportunity long-term planned Scott McLennan of the State University of New York, at the time.

By mid-year 2014, however, Opportunity was experiencing problems with its aging memory. The rover used Flash memory to store information when it went into hibernation during the Martian nights, which take place about as frequently as they do on Earth. 

Controllers did a remote memory wipe from Earth, but memory issues and resets continued to plague the rover through the end of the year. Eventually, officials elected to stop using Flash memory, move storage over to random access memory (RAM) instead, and find a way to address the problem more thoroughly. In 2015, NASA decided to use RAM in most situations, which requires Opportunity to send high-priority data right away as the information cannot be stored if the rover is off.

Despite these issues, Opportunity continues rolling on the Red Planet. It set an off-world driving record in July 2014 when it successfully passed 25.01 miles (40.2 kilometers), exceeding the distance from the Soviet Union’s remote-controlled lunar Lunokhod 2 rover in 1973. In March 2015, it passed another huge milestone: completing a marathon on Mars.

The rover successfully imaged Comet Siding Spring when the celestial body sped fairly close to Mars in October 2014. In January 2015, Opportunity took pictures from a “high point” on the rim of Endeavour, about 440 feet (134 feet) above the surrounding crater floor. In March 2015, NASA announced that the rover – while overlooking an area nicknamed “Marathon Valley” – had seen some rocks with a composition unlike others studied by Spirit or Opportunity; one of the features was high concentrations of aluminum and silicon. 

After working through a Martian winter, in March 2016, Opportunity tackled its steepest slope ever — reaching a tilt of 32 degrees — while trying to reach a target on “Knudsen Ridge” inside Marathon Valley. As engineers watched the rover’s wheels slip in the sand, they decided (with some reluctance) to skip the target and move to the next thing. 

NASA announced it was wrapping up operations in Marathon Valley in June 2016, and added that Opportunity recently got a close-up look of “red-toned, crumbly material” on the southern slope of the valley. Opportunity scuffed some of this material with a wheel, revealing material with some of the highest sulfur content seen on Mars. NASA said the scuff had strong evidence of magnesium sulfate, a substance expected to precipitate from water. 

As of August 2017, Opportunity was in a location called “Perseverance Valley” on the rim of Endeavour Crater, and the rover had traveled 27.95 miles (44.97 kilometers).

Courtesy-Space

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